I can only really say what I've got... I got mine from EcoWatch (which is part of Heligan Gardens in Devon) it's a high resolution, vari-focus colour camera, with a separate infrared light for black/white night viewing. I also have sensor software, so that it records footage onto my computer if there is any movement. It seems pretty good. I've already had some quite decent footage, some of a
robin bathing (which is on my online diary) and some of a small mouse, foxes and birds at the feeder. Hoping to use it for fox cubs in the spring (if I have any this year under the shed). I also took one of the frames as a picture of a robin in flight.
Yes, the more lines the better (as far as I can work out). I started off with a low resolution camera (which was pretty awful), my new one is a lot clearer, better colour, quality, etc. It is a wired setup but you can also get wireless. Easy to setup (you get all the instructions included). However, I'm sure there are cheaper suppliers - I went with these guys because I needed a complete setup from people I could go back to for information. They have been very good. I'm sure they do a kit for about £200.
Hope this helps
Jane