So I started out playing Minecraft for free on my account until I could buy the online version so I could play with friends. I just bought the game today and I keep getting a "can't connect to minecraft.net" and the options to try again or play offline. Did I just waste $25?

I'm new to minecraft and I have a few questions:

1) If I find a cave, what are the chances of there being diamond and obsidian deep in it? I don't want to spend an hour digging through a cave just to find a lot of coal

2) Would it be wise to put my base above a cave? Or since the cave is finite in resource it shouldn't matter where I put my base?

3) What are the chances of finding diamond/redstone/lapiz lazuli by just finding a spot and digging down?

4) Lastly, I want a seed that has a forest, plains, and a lake with animals. Can anyone suggest a good one for me?

Thanks!

(i know these boards are probably dead, makes me miss them being full of life) but, whenever I use paciencia, Bozar, or Medicine Stick, sometimes the bullets don't make contact with the enemy even if the tip of the sight was on the torso. I experimented with it using a pack of raiders and saving/reloading and I was right. Even at about 30 yards away with the sights right on the torso, the bullet would glitch and not make contact and thus do no damage. Even occasionally in VATS with 95% (no, the bullet didn't hit anything in between me and the enemy). Anyone else experience this?