Yeah, for visiting the LHBS, just add more base grain if you want it to be a few points higher, or have some dry extract laying around to toss in. Since it sounds like your values are fairly consistent though, you can change the efficiency in BS when you're creating your recipes (labeled Tot Efficiency, middle of top of the Design tab in mine). Set that to 70% and you should be able to get pretty close to your results.
The way you're doing your strike water, you only really need to worry about the strike temp. At the time that you mash in, your equip is already at the same temp as your water (since you add it hot and let it cool down), so you don't want to have that one checked. In my case, I don't preheat (even though I know I'm supposed to), so I make sure its checked. The first few times I mashed in I made careful note of the temps and slightly adjusted the Mash Tun Specific Heat until it gave me what I was seeing, so I don't bother preheating now and get close enough for me.
Again, with the deadspace, phoenix has got it right. The best way is to fill it up, then see what you have left as a result. Anything that's left in the mash tun, BK, chiller, etc., can all be entered in as deadspace. Personally, I went the trial and error way and just made sure to carefully measure the water I put in on the first batch, and how much I got out, then changed my deadspace values to match up with what I was seeing. I got a little bit higher gravity since I had to boil down a little longer, but I was ok with that for that first batch. Everything since then has been pretty close.