You can add as many lineups/channels as you need in schedules direct. I created the Kodi addon interface so people didn't have to use the SSH manual setup to do all of that.
You should have no problem running LE on the Pi 3 with the backend and frontend of TVH addons enabled. That being said, make sure you have a fast sd card as that impacts the cache performace. Depending on what you want to use for recording, you'll want to make sure that has a fast transfer rate as well. That way if you're recording and playing back at the same time, you don't have a buffering issue.
I didn't know a thing about python when I started piecing together my addons (zap2xml and sd4tvh) - I just built on others work and looked up whatever I needed to. SD4TVH isn't really a clean build as it is pieced together from two other projects...but it works and makes the schedules direct setup a lot easier for people. Maybe someday I'll have time to build a cleaner version from scratch (or someone else can) but for now - it hopefully get a lot more people to cut the cord!
If you have any trouble running the addon - let me know!