haha awesome mecha! Ok a couple things:
Is this something you built or downloaded? (pm me link to rmf and i can give you more-detailed evaluation)
I wouldn't worry about things being off-grid, but you can always try selecting the item and hit CTRL+B to "snap to grid".
You can prevent hammer snapping your geometry to gridpoints by using
Jed Smith's HLfix. Even better, using
Atom's Compilator, you can easily and quickly enable HLFix.
I would recommend ANYONE who maps for goldsource to use Compilator and Hlfix.