I like the Oasis nail shaper, available on Amazon or Strings By Mail: see who's got the best price. They don't do much for taking off length, but the four sides let you do fine shaping, and give a nice glassy-smooth finish to the nail edges. They are disposable, and, I suspect, recyclable. Also, the glass files by SBM are fantastic: while very fine-grit, they'll cut through anything, even fake nails, and leave a smooth finish.
For that matter, SBM has a nail-care kit for classical guitarist which may fit the bill for you, and has several products to try.
For maintenance, I'm not a big believer (just a personal thing) in nail-polish type strengtheners, or anything that has to be removed with acetone. I prefer to just use a very rich hand lotion on my nails daily, and try to use rubber gloves if I have to immerse my hands in water for any length of time (eg, cleaning the kitchen or bath). If I do break a nail, I've been experimenting with the drugstore equivalent of Rico Nails (my hands are small), because I can use a temporary adhesive that lasts only a few days, and doesn't damage the natural nail so it can grow back healthy (no superglue adhesive).
Hope this is some help!
2015 Connor spruce/Indian rosewood
1978 Ramirez 1a cedar