Semi-beginner questions...

I'm somewhat newish -- and extremely new to on-line chess, this site, etc.  So, I have a few questions:

I've played a grand total of four rapid games.  Don't look them up -- although I've won them all, they were all very mistake-prone, and few blunders, by both sides -- and looking back at them, it's pretty embarrassing.  I'm *guessing* that the reason is that 10-minute chess is just too fast for me at this point.  My questions related to this are:

• will 10-minute chess build any skills at all?  Perhaps some instincts, etc.?  Or is it just entertainment value?
• Or is it sort of a waste and should I go for longer games?  
• If I go for 30-minute games, will I be facing folks who are using engines, etc.?  (I initially figured that with 10-minute games folks wouldn't have time to do that so much)

Thoughts?

Hi. 10 minute chess will not help much with improvement. 30 minutes is much better, longer the better. My guess is engine use will be much lower in slower games, people play slower games to improve so take their games more seriously on the whole.

Play Longer Time Controls...

For many at the beginner-novice level, speed chess tends to be primarily an exercise in moving pieces around faster than your opponent while avoiding checkmate, in hopes that his/her clock runs out sooner than yours.  Or being lucky enough notice and exploit your opponent's blunders before they exploit yours.

The point is, there is little time to think about what you should be doing.

It makes sense that taking more time to think about what you should be doing would promote improvement in your chess skills.

An effective way to improve your chess is therefore to play mostly longer time controls, including "daily" chess, so you have time to think about what you should be doing.

This is not to suggest that you should necessarily play exclusively slow time controls or daily games, but they should be a significant percentage of your games, at least as much, if not more so than speed games which, while they may be fun, do almost nothing to promote an understanding of how to play the game well.

Here's what IM Jeremy Silman, well-known chess book author, has to say on the topic...
https://www.chess.com/article/view/longer-time-controls-are-more-instructive

And Dan Heisman, well-known chess teacher and chess book author…..(the link may be slow to load)…
https://web.archive.org/web/20140627052239/http:/www.chesscafe.com/text/heisman16.pdf

https://www.chess.com/blog/RussBell/dan-heisman-resources

and the experience of a FIDE Master...
https://www.chess.com/forum/view/general/how-blitz-and-bullet-rotted-my-brain-don-t-let-it-rot-yours

I agree with everyone here however, 10 is wayyy better then blitz and bullet

Chess Engines (i.e., computer calculation of your moves) and human assistance are illegal for all forms of chess, both live and daily during active games.  However for daily chess it is always legal to use passive sources of assistance such as books and databases etc.  

Even in blitz there are people who uses engine, so don't that be a reason not to play longer games. 15|10 is probably the shortest time control to improve for most of the people. If you play even longer games, so much the better.

Newbie question: what is "15|10" ?

15 minutes per side + 10 seconds increment on every move.

I agree with MarkGrubb.  The longer your games, the better. If you are fairly new, you really need to take the time to think about your moves and understand what the opponent is trying to do.  Understanding cannot be rushed.  If you want to play a lot of games you can always play several longer games at the same time.