Ike- The nail holes are a simple solution; use colored wood putty on the planks that are face-nailed, working as much into the hole as possible. Do not use a knife or spatula that might scratch your floor; fingers work best, then wipe clean with a rag dampened with acetone. This will not harm the finish of the floor as long as the rag is only slightly damp, but will help to soften the edges of the putty, causing it to blend into the wood better. Try mixing colors to simulate grain. Gaps in the end joints are difficult to deal with, considering that 3/4" planks are nailed in place. If you can't bear to look at it, try some of the putty. If you don't like the way it looks, you can take it out, and/or put a rug over it.