What he said right there!!! At one time or another I'll use just about any glue or filler under the sun. Right now my favorite filler for most things is straight super glue! But the bottom line is that there's more to those questions than can be discussed in this space and they get rehashed on a regular basis. If you find a club, the members will be glad to discuss any question you have for as long as it takes and in the exact situations you're facing.
The boards (like especially this one!) are great sources also and a lot of different people who know a lot of different things will get to see your questions.
Of course, number 3 is the most important. HAVE FUN! Use any kind of glue you want if you feel like it! They're only plastic models!
And, WELCOME BACK! I took years off, too, and the learning curve was steep for a while but you'll be amazed at how soon you're on top of it!