Like others have said, welcome to CF. It is a fun game, but there is an undeniable advantage to having played for longer periods in terms of just knowing how to get around/level/rank/pk. The best way to improve at every facet of the game is simply to play. Use the forums and such as a resource, but always remember experience will be the best teacher. The easiest way to get experience is from other players. Reading maps and item info is nice, but you'll find other players that know that stuff can point you in the right direction quicker.

For some of your suggestions here are some thigns that exist in game maybe you can use (lots of which you might already know):

PK academy - That's a tough one, since most people want pks. That said, you can usually find people (they don't have to be in pk range) and challenge them to an arena fight for training. There is no consequence for defeat there and you can probably find someone to help you with tactics, especially if you are new. A cabal can help with this too, you can have cabal mates "spar" with you and help you improve. In my more active days I did this a lot. I would sit there as a hero and let lowbies try things against me and we would talk about methods of fighting. All while in the safety of the arena, as I would break off the encounter before either person was defeated. So long as nobody is waiting to fight, and you're not doing it solely to avoid PK, I don't think anyone has a problem using the arena in this manner.

XP academy - This is more of a general experience thing. Ranking with others is nice, but it also can enable groups to take down things you would not want to solo rank on. Improved consider is nice as it will tell you the class of the thing you consider. Knowing how NPCS track can also help you avoid deaths. We'll all suffer a few NPC deaths in ranking, the aim should be to avoid the ones you can. There's rarely a reason to be fighting a mob below 50% health while you are ranking if it can lag you for example. Sometimes you just get unlucky. As to knowing where to go to find mobs, the levels of areas are pretty broad. Try to stay within your range or slightly above and you should be okay. ALso know that melee classes generally have more hp and better defense, so it makes them far easier to rank with vs. mobs that rely on passive melee for a lot of their damage. As a mage you generally want to gear for hp to make up for the poor defense, or find a decent tank person to group with and that act as just a damage boost.

Newbie Imm/cabal- If I was at all capable of being an Imm, which I'm not, I would have been the newbie patron. That said, most all the Imms are still a very useful resource as they'll field prays and answer questions on the newbie channel. An Imm probably can't get to directly involved in protecting your char just because you're a newbie though, there is an RP divide there between their Immortal char and their role as admins. Some of them will lead some fun RP encounters if you happen to be around though, and I'd suggest trying to involve yourself in those when they come up.

As for a newbie cabal. Fort acolyte should put you in a pretty friendly group of people. And of course, the real best bet is play a neutral neutral non-mage herald, and you'll have no real enemies (though evils will still pk anyone they want). Heralds love helping people and going all over Thera, and joining the troupe is pretty easy.

Basic gear- Play a race that gets 100% lore or play a bard. Lore everything you come across and keep little mental tabs on it. Honestly, pre 25 I wear mostly bramblefield merchants because it's decent gear for the level and other stuff is too tough/time consuming to gather. Knowing what to gear for is probably more important than knowing all the gear in Thera. If you make it to hero and get the legendary awareness skill, keep it up all the time. Seeing something that is rarer might be worth acquiring to lore. Even if your current char can't use it, a future char might. Look at what other chars are wearing, ask where it comes from. As it's IC, you'll find out things like quests in addition to learning where to get some gear people generally wear.

Heroing: It's just a matter of the right group for most players. Fostering IC relationships is pretty useful. Having a hero friend to help out when they are bored for example. There are mercs, but they incur a penalty (unless the merc lands the KB on the guy, which for some reason seems to make the penalty not as bad) I also don't know of many really useful mercs past level 25. A PVE only based merc would be a neat idea.

I know, none of this is probably very helpful, but wanted to try. I remember my CF newbie days. My first char was a half elf c/e assassin (what could go wrong!). Here are some highlights:

I got pk'd because I hid on the balator road when I saw someone coming, and didn't know the hide skill could fail (or that it had an echo if it didn't work). An arial walks up and two rounds me.

I died at least three times in the sewers trying to get the silver rapier, which was by far the best weapon I ever got.

I went ranking with orcs, got betrayed and PK'd because I was slowing them down. They apologized (in an OOC fashion) once I told them I had no idea how to get back to my corpse

I took the oath because I wanted to stop being killed by imperials.

I got anath'd for not retrieving the codex because I had no idea how to get to the fort cabal. (I got pk'd by imperials even worse after that.)

I con died at level 32, I think in well under 100 hours.

That's all I remember. My second char was infinitely better. And that one might still be one of the worst chars to have a pbf published.

None of which is to suggest I didn't have fun or learn with either of them.

So if you're having fun, that's really the best asset you have in CF. The rest comes in time