I can't help with the clipping, as I don't do it, but bathing shouldn't be done too often. I try to only bathe a horse once a month IF, and only if, the horse is dirty enough to cause the horse to scratch or itch themselves or if they are so dirty they can't be spot-cleaned or brushed out. I think once every month or two in the summer would be good.
Any more than that, and the hair will be stripped of the naturally good oils.
If your horse sweats a lot, washing the horse with only water is fine to do after every sweaty ride or training session. In fact, horses love the extra cool down. c;
For showing season, stick with bathing only before shows. Be sure to bathe a few days before the show as well, so that the natural oils can return a bit and add some shine to the horse.
In the winter time, I rarely bathe horses. First off, I don't want them to get chilled. Second off, we don't have warm water. I will occasionally get a bucket of water, heat it in the microwave, and sponge bathe horses if they have a bad spot that needs out. But then be sure to dry them off as quickly as possible and/or throw a blanket onto them until they're dry.
If your horse is like the typical white coated horses, spot cleaning might need to be done frequently. If so, just get a jelly scrub, curry, etc. and some soap and only try to scrub that area. The less you bathe them, the better.
As far as clipping, I would only do so if your horse is shown in the winter or is a wooly mammoth all year-around. I see it to be a pain to do. The boarders always look forward to the day they get to fight with their horses on who clips who. ;D lol!
Only clip if you really think it's needed. Why make more work for yourself?
It's where I learned about working hard
And having a little was just enough