I do believe that threads are automatically closed after a set time with no activity (but stand to be corrected). There's no problem with starting a new thread on an old topic -- typically the new thread starts with a link to the old, so that people can gather background if so inclined.

As for picture size, I think that is connected to which method you use to post. I put my photos into PhotoBucket and link from there, and they come through at a reasonably large size. I've set PBucket default to "forum size" or some such option, so PB automatically sizes my uploads for that type of use.

I think the smaller photos/thumbnails result from posting a photo directly from your computer. I haven't figured out how to do that, and knowing that they come up so small I haven't bothered to learn. Much prefer the extra step of going through PBucket to get a nice photo posted vs. those little postage-stamp sized ones. . .