You have to edit the sprites of your screenpack, or change things in the "system.def" file in this case.

To remove the random icon in your select.def file search for a character called 'random' and rename it any other way.
Meanwhile in your system.def file there's the option to make empty cells selectable. Disable this option.

Time after time as you progress, do test runs on the fighters you're doing and check to see if they're going the way you intended them to go or not. It's important you want to make sure the fighters are fully prepared.

The attack is either using targetlifeadd. Or its putting p2 in a custom state. Look for p2stateno or targetstate in the attacks code follow to the state in question and there will be a lifeadd in that

LOL don't worry. People used to tell me the exact same thing years ago & I even responded the same. Don't take this the wrong way, but... Do it. Talk less. Show by action. People love to say what they want or will do, yet never get past the front door. You've already explained your intent, now all that's left is for you to put the work in. 

Please post compilations in Mugen Discussion.

The best advice I can give you.. Decide what you want to do, then do it. Sounds simple enough right? You aren't going to learn going straight to the books. Try what it is you want to do, then you'll gradually discover what it is you lack/need to learn how to do. Taking it all on at once can be overwhelming. Set small goals, make those edits to learn what does what. As long as you have the imagination, you'll see procrastination is your only enemy. IMO, forget about anyone else helping you, you want something done, well I'm sure you know the saying.

Nah, I can't. You need to know about MOST of the whole stuff that goes under the "SCTRL" and "TRIGGER" filters to do a thing and do it right. So you'll have to put your time in it. But, as a babysteps, take a look at a controller "HitDef" and a trigger "animelem".

Well, can give you nothing about the game itself since that's for now just compilation.
But I can give you advice on how to get started: MUGEN Class. Go learn some SCTRLs and Triggers, those are pretty much basics of chars, all the other stuff there is something more advanced.