A little bit of echo definitely helps get the 'hot' country sound, I go from 120ms to 200ms with one repeat. The level shouldn't really be very high because you just want to thicken the sound a bit and add some spring. You can turn the level up a bit if you want rockabilly slap back. I have a DD-20 so I put it on the analog setting with the tone backed off a bit and it sounds pretty good. Sometimes you need longer delays for country stuff and a bit of chorus can come in handy, especially for the slower more modern songs.
You need to decide whether you want to be able to have the really really clean sound (Jimmy Olander sort of sound) or a bit of hair (i.e. Brad Paisley) or both. If you get an amp with a lot of clean headroom obviously you can add hair to taste with a tube screamer or something but you'll always be able to do the snappy clean thing and have the best of both worlds. I love that sound but have a Deluxe Reverb so unless I'm miked up I usually have to accept that I'm going to have a bit of breakup (but if it works for Brad Paisley...
). Just something to bear in mind if you're amp shopping.
I think compressors really help nail the sound and the feel for chicken pickin' country guitar but there seems to be a 50/50 split as to whether or not you should use one. All the info above tallies absolutely with my experience of comps. If it helps I find tele (with lowish output pups) into compressor into delay into amp gets me there. For me that is the instant nashville chicken pickin' recipe. I have the reverb barely on if at all and plenty of treble. After that, as stated above, I think it really is all down to technique and in particular how you pick and snap those strings.
Final point, for me half the fun is experimenting and finding the sounds. You can always resell gear, especially pedals, and the used market is part of the fun. I've had quite a turn over of gear recently to find the sound I was after and I have enjoyed every second of the process. If you search out used gear and read up on sites like this you can usually sell on what doesn't work for you with little (if any) financial loss.