Ok lets share my findings in case anybody ever bothered.
1 - cap option on extrude tool doesn't work for real, on the other hand what does cap's work is: vertex > create ordered surface (for 3 vertices) if more then use rather: vertex > create 2d mesh (select appropriate perspective) followed by several: surface > combine.
2 - Tools > Render to texture > Tick first three options
3 - vertex > snap together
4 - there are minimal support to secondlife's sculpted maps, the only supported way is to use the sculpted examples provided by ac3d as a base start, then surface > divide and combine are your friends along with manual aligning of vertices (just like actual sculpting
