I've been playing online for my last probably 20k hands out of ~50k total using a HUD, problem is I'm just starting to really study and learn about odds, equity, etc, and I find that I don't really think very hard about these things because my HUD basically tells me all that information, and then all I have to do it put it to use. I realize that this is the point of using a HUD, at the same time I'm worried that maybe I'm not actually learning as much as I should. For example, what do I do in a live game when I actually have to calculate the **** in my head? Would it be a bad idea to turn my HUD off so that I can work on my game? Is it better to leave it on to keep a slightly better edge on my online opponents?

I consider online as just practice for live and I try to make as close to the live experience as I can and hence never have and never will use a HUD. I think using a HUD would make it pretty boring. But thats me and I am sure others will stronly disagree.

I strongly disagree, I'm trying to win money and will use whatever I can within the rules to do it.

Each to their own I guess

HUD's don't really calculate that much for you, they just keep track of villain's tendencies and give them a numerical figure. You do the same at a live table but without the numbers. When i first started using a HUD, i found my live game improved drastically as i learnt what aspects of a players game i should be concentrating on. On top of all that, the advantage of using a HUD is MASSIVE!...in most cases the difference between a positive and negative winrate. You just need it man!

That being said, it's important to practice the discipline of watching player tendencies. Perhaps play a few hours a week without a HUD at a lower stake to keep you in shape.

using a hud is fine so long as you don't become a hudbot and use it as a replacement for thinking for yourself and making reads for yourself

I recommend beginners have a very simple HUD at first, with just VPIP, PFR, 3-bet and AF. Those numbers are all you need to give an idea of someone's tendencies and allow you to categorise/colour code someone. Then you can devote more time to watching how a hand plays out. You'll also be clear about who you're up against when you play a pot. If you make TPTK and see villain is playing 33/3, you can be fairly sure he's a station, so go for max value. If villain has more TAGgy numbers like 14/12/4 then you know you have to be a bit more careful in a hand with him.
Your tracker will be calculating lots of other stats while only displaying the main ones, and you can start adding things like c-bet, WTSD and "fold to 3-bet" to the HUD once there is enough data for them to be useful.

I have a question about steal stats in HUD, is is effective to use that? I have noticed on some players that it only shows 0 % over 100 hands or something or a very low number and it doesnt seem to be accurate.

Personally, I find steal stats very useful. I like to know who I can steal from (the nits w/ high "fold to steal %") and who is going to try stealing from me (the tags and lags w/ ATS of 30+). The steal stats also give a good indication of whom is positionally aware. Players who aren't tend to have wider ranges in early position, so you don't have to fear them so much when they raise UTG.