what is the sole purpose of joining a guild. do you get extra benefits???...do you get to play each other like a league. also is the infirmary worth having and is it worth it. does it give you anything extra. I know I been asking a lot of questions here lately. but I'm new to this and I'm just trying to figure out what is the best path. thanks in advance for any replies.

Infirmary is awesome for regular players as players get back to full health quicker. Guilds have guild v guild challenges which are fun but I think they could tweak the guild league system to make it dependent on results

Joining a guild would depend on the guild, of course. Some can be helpful and the people in the guild should be able to answer questions you have that will not be answered on here. Plus they help with getting more points for AH through Guild Challenges, as long as you upgrade your guild hall. And maybe you like to chat and you can do that in a guild.
Infirmary is a big help. Not only will it help your players get back to full health faster, but this also helps when training; you get more experience with your players at full health..

To show you how important the infirmary is ... last night I put my players on the 36 sapping energy training right after my league match. Then as I slept a much weaker team beat me 19 - 13 in a friendly. Rewatching my match my defense missed so many tackles.
I rechallenged them this morning with a full strength team and destroyed the opposition, my defense getting 3 turnovers.

thanks yall for all the info

Depending on how hard they need you to play, GCs are great for extra cash, too.