I can answer some of your questions . Someone’s surplus clubs cannot be gifted to anyone , at anytime. The owner of surplus clubs can only sell them and perhaps use the credits they get to buy you clubs. Clubs can only be bought up to your level , you cannot buy clubs above your level except under certain conditions. Those being if they are bought as part of a bundle.
It is only credits that buy most clubs , not coins. Some clubs can be rented using the coins , but not very good ones. The coins are used to play in the coins rooms in one on one match play. You need to either buy credits , or watch videos, do surveys or take up offers , to gain credits. You are allowed to watch 75 videos per day to earn 150 free credits per day.
If you play mobile in the app , those ctth courses you mention , are only ctth courses you cannot play them as full courses in mobile.
I am level 118 and I still do my sponsorship for apparel , mainly because if you can max out your apparel you get greater attributed benefits and win higher level of coins. Those coins I then use to play in higher coin room matches in turf war. You need coins also to upgrade apparel.
Personally I would say you should by now be playing ranked rounds , but it’s entirely up to you , in order to progress to the higher tiers , the ranked rounds is the most used method of getting there, though in mobile there are other methods too.
hope that answers most questions , feel free if further explanation is required , to come back