Maxamps, pfft. Most BL escs have built-in LVC devices these days- it'll say in the specs. Brushed escs not so much, evx2 doesnt, thats true, but a 4s LVC isnt really the best option- read the LVC section of my tutorials page:
http://robotwars.00server.com/tutorials.html
Silver can 540 motors will be really weak and slow on an emaxx- thats what the tamiya TXT-1 comes with stock it its anything but impressive for bashing. Buying online is pretty much required- the stock 21t titan motors will be fine, but there are plenty of other options for brushed motors, check out
www.kershawdesigns.com, or hit up ebay for some dewalt 12v- 14.4v motors...
Yes, lipo & Life cells can be used just fine- electricity is electricity is electricity after all, you just have to observe the voltage of the cells vs the rated voltage of the esc. The evx2 is rated for 16.8v/ 14 nimh cells, so 2x 2s lipo is fine ( 4.2v per cell fully charged ), as will be 2s+3s LiFe ( 3.6/3.7v per cell fully charged )- just plug the 2s LiFe cell into the BEC side of the esc ( see: tutorial page again ).