Rear dropout adjustment screws on fixed-gear conversion I have a Surly Cross-check that I absolutely love and adore to pieces. I've also converted it from a geared bike to a fixie and am wondering if I still need the adjustment screws (see picture, in case you don't know what I'm referring to).

The issue I have right now is that my chain is a bit slacker than I want it to be, but with the current position of the adjustment screws, I can't move the rear wheel any further back in the dropout. Are the adjustment screws necessary at all on a fixed-gear bike, or are they only needed when you've got a derailleur system? I'm a bit clueless on them, this is the first non-vertical dropout bike I've owned.
They aren't necessary, but they are a great help to properly aligning your wheel in the dropouts in an efficient manner. If these screws are adjusted correctly, you'll be able to just put your wheel in, pull it all the way back and tighten your axle nuts and your wheel will be arrow straight in the frame. If not, You'll need to manually align your wheel each time you take your wheel off to change a tire or do maintenance.

To solve your chain problem, you can either adjust the screws out so you can get your wheel further back in the dropouts or you can remove a link or two in your chain.

Either way, you want to make sure that the axle nuts have a good bite on your dropouts. This means that the entire nut is in contact with the dropout (save for the portions that are aligned with the openings)