1) Joel said you could use any export format, but do NOT use obj
2) A quick test showed me a number of 13k vertices, I think, that's the expected number. Maybe smooth shading and adding a subdivision surface modifier can help.
3) What scale unit did you use on export? Decimiter (= default) means 1 blender unit (BU) is 1 decimeter in MH, i.e. a model which is 170cm tall in makehuman will be of 17 units in blender. When choosing centimeter on eport it will be 170 BU.
4) It doesn't help, you will have to learn any 3d modelling program if you really want to use the models. For Blender there are many tutorials on youtube, and there are links to them on the wiki page.