My 7 Month Old Boy Only Sits up for About a Min. Before Falling Over..

Oh yeah! Rolling over (front to back, back to front) comes first, then slithering, sitting and crawling. All the moving is good. Pulling up to his legs then cruising (hanging on while walking) will come along (and then they climb Everything even before they can walk). You've got a little time before you need to start baby proofing everything, but you might as well get started now!
The daycare where my son use to go had these bouncy seats (baby would sit on the floor, but a harness would hold him to the seat which kind of propped him up). The babies could push back (try to lie flat down) and the seat would bounce them back up. My son LOVED that thing!

Absolutely. he's just coming up on the age for those things, so relax and enjoy it. Before long, you'll be tearing your hair out trying to figure out how to keep him out of stuff! PS Spread his legs out for better balance when he's sitting on the floor.

I wouldn't worry too much about it. At 7 months my son was not able to sit up unassisted for long either. He is almost 9 months now and is able to sit unassisted. You'll be surprised at how fast they are able to do new things.

My daughter was literally walking before she could sit up for any length of time before toppling over. Grandma joked that she had such a round bottom, they'd have to tie her to her chair in kindergarten to keep her from falling off.
It's just a matter of getting the balance thing down. In my daughter's case, rolling over and just getting on her feet was easier for her.
If your son is starting to crawl and scoot himself, next thing you know he'll be pulling himself up on furniture and "cruising".
I don't think you have anything to worry about at this point.

After having 8 children I would say to not worry about the age they do anything unless, of course, it's WAY behind. It's not uncommon for some babies to not sit up until 9 months or so and personality, weight, etc. all play a part in it as well as when they want to stand and put pressure on their legs. Some little guys are just happy to sit and play. Boys seem to be more into 'things' than getting around although some are off early. One nephew was walking and climbing by 9 months and believe me you don't want that. His mom couldn't keep him from getting into anything. Just enjoy your little boy and let him go at his own pace. I used to prop the kids with a big blanket or quilt that would go around them and if they toppled over it didn't hurt them but even that is up to you as I'm sure he's happier doing his own thing. Soon he'll be going all over.

I wouldn't worry. My 10 month old just took his first steps and he can't pull up on furniture or crawl with his belly off the floor yet. Some kids just do things in their own order when they are ready. My friend's 10 month old is not super fond of standing, but will if he has support. He can even cruse on furniture, but he's really wobbly holding onto someone's hands. Every kid is different. :)