Questions about 2 things that happened to me in DiabloII

I finished DiabloII on normal and I'm into ActII on Nightmare and some different things have been happening to me and I was wondering if there was a reason for it.

For one thing, in ActII I did the quest where I killed Radament and started the other quest. The next time I loaded the game up and went into quests it said "KIll Radament". I already did it but now its back, I was wondering if u know why that happened.

Another thing that happend to me was that I lost over 20 skill points in my strength, vitality and dexerity. What the hell happened there, is it something to do with playing in the Nightmare difficulty? I had good armour that I needed 100 strength in order to wear it and now that I lost those skill points I cant wear it and it pisses me off lol.

The last thing I was wondering, is there a good website about DiabloII strategies, gems, weapons, maps and other good stuff like that?

Thanks.