Started with the right-hand side, got bolt 1 in the sequence loosened, went to do #2 (deep in the cylinder head) and am just now realizing I need a deeper socket. All the relevant stores are closed. Do I need to worry about warping now that one head bolt is loosened while the rest remain torqued down? Or am I good until I can get a socket?

 

It'll be fine, its cold so not a lot of movement. You can always just snug the one you loosened down if you are worried about it.

 

No, one bolt being lose will cause no issues.