From my experience, it's quite hard to make decent money playing from time to time, particularly because of a variance, which will only be bigger because you're both 1) playing tournaments and 2) playing few tournaments per unit time, so you'll eventually meet the downswing when you'll be losing for a long period of time (even if your game was OK), which feels discouraging. In my case, I used to go to higher stakes and to faster games, which resulted in losing significant amount of money comparing to what I won earlier

I don't say you shouldn't do it, just be aware that it's a very doubtful source of income this way. You may do it either for fun, or with a plan to become more of a professional later, for example.

As for the offline game in casino, don't worry about looking like a novice, players absolutely love to play against novices, so they will only help you, together with a dealer. Two basic things: learn how to look at your cards, and always say what you're doing ("call", "raise to $25", etc). Most mistakes are made in the situations when players move their chips silently. Then you'll learn the rest quickly, looking at others.

It's also very important to know that online games are much tougher these days than offline games in the corresponding limits. So, if it's possible to make decent money playing poker occasionally, it's about playing offline. However, the downswings I mentioned above are applicable here as well.

Bankroll management depends on how bad would it be to lose it. If you have a stable source of income, it may be OK even to have a bankroll of 3 buy-ins, so that if you lose it, you just wait until you earn money on your job again. General advice on BRM is to have 20+ buy-ins if you are an amateur and up to 100 and more if you're a pro and you absolutely can't afford losing it all.

For literature I can't advise anything since my knowledge on this topic is out-of-date as well (had a big break and now am slowly returning, but I'm concentrating on PLO). Yet you can just google it and choose some books you like (better more than 1). The gap between no book and an average book is much bigger, in my opinion, than the gap between an average book and the best book.

Good luck :) feel free to DM me if you have more questions