FSDS3 ?'s

Hi, i just recently purchased FSDS3 cause i about ran out of things to repaint lol. Im currently working on a P-61 Black Widow since there isnt a nice P-61 out there. Ive gotten pretty far on it but now im at a stand still. The questions i have since im sure some of you knowledgeable people
1) As you can see in the pics below, my pieces are not bonded together so you can see where the pieces are at, how cna i combine all these so the whole model looks smooth?
2) FSDS3 says it has unlimited undo/redo which i cant do, how may i acheive this cause i mess up a lot right now
3) Also, when i get it completed, how do i put panels and textures onto the model?
Once i can figure these ?'s all out i will be producing a lot of types of models of airplanes i like.
Heres some of the pics of my work:




1) As you can see in the pics below, my pieces are not bonded together so you can see where the pieces are at, how cna i combine all these so the whole model looks smooth?
2) FSDS3 says it has unlimited undo/redo which i cant do, how may i acheive this cause i mess up a lot right now
3) Also, when i get it completed, how do i put panels and textures onto the model?
Once i can figure these ?'s all out i will be producing a lot of types of models of airplanes i like.
Heres some of the pics of my work:



