Carpentry and Woodworking - fitting butcherblock countertop

i'm installing new cabinets/ butcherblock counters in our kitchen and am preparing to do the countertops. the kitchen is u-shaped with a long stretch in the middle (about 15 feet broken up by a sink and stove) and shorter sides (3 feet on one side and 6 feet on the other side). I have a couple of questions

1) break in the long stretch: my stove comes in about 6 feet from one end, so i'll make a cut there, but as for the remaining 12 feet or so, i'll need to use two pieces of wood. where should i make the joint? i've seen it done at the center of the sink. is this recommended? if not, where is the best place?

2) how to join the 90 degree corners: i've been told i need to do this as a butt joint rather than mitered joint. what is the best method. also, what do i use to connect them to get a tight and smooth top? glue? caulk? (i don't have a biscuit joiner, so that's not really an option...)

3) dealing with a wavy wall and odd corners: whats the best way to get it to fit a wavy wall (besides taking everything off and flattening out the wall)? we will be adding a tile backsplash, so that will cover some gaps -- but i need the counter to be within 1/8-1/4" of the wall...

thanks in advance for the help!!

1. I would place the seam at the sink, because it will be easier to manage the installation and the cutting. It will leave the least seam there.

2. Here is a handy device to join the countertops.

http://www.growinglifestyle.com/us/article/s0/a1174295.html

3. To make the top fit, set it in place and scribe along the wall with a compass tracking on the top. Trim the top along this line to get a tight fit. Then install the backsplash.

Hope this helps.

thanks. two follow-up questions:
1) what should i use to seal the seams? i've heard of using a silicone caulk. will that have the holding power i'll need. also, since it's wood, i'll be able to sand the seam a bit to get a smoother edge -- but i'm not sure how well the caulk will sand...
what about an adhesive like liquid nails, etc?

2) what about cutting along my scribed line on the counter top -- is this the work of a jigsaw (mine doesn't turn so easily) or is there another/better tool to use (something i'll probably also need for the sink cut-out.

thanks.