I have a compressor and use spray guns. They may of improved these "Airless" guns by now, but I have never had much luck with them in the past and considering the cost of decent compressors these days that's the way I would go. Also noting that a compressor allows the use of other tools like nail, pin and staple guns, Tyre inflaters and blowers etc.
I almost 100% of the time use lacquer, either automotive clear or that designed specifically for wood. I have tried water based but it does nothing for me, considering the principle reasons for finishing timber. 1 to protect the item. 2 enhance the look.
Lacquer dries quickly, cuts back easily, and you can rapidly apply extra coats to improve the depth of finish. Finishing is a vital part in the completion of a piece, just like sanding, designing. cutting and assembly etc so can not, should not be, looked upon as just a quick necessary step to get you item out the door.