Groups: From what I see you are anticipating the recoil and pushing the gun a bit. This is normal as you begin shooting larger calibers. Best way to combat that is
1) Shoot a lot
2) Do quite a bit of dry firing. This exercise is to get the trigger to break - without - the end of the barrel moving. A portion of that exercise is to balance a penny on the end of the slide and practice. If the penny drops before the hammer hits, you are jerking the trigger.
3) Try to have the trigger break (release of the hammer) be a surprise (slow squeeze).
4) Make sure you do not put "too much" finger on the trigger. Many people will put the knuckle on the face of the trigger. This induces a bit of lateral movement in the gun. If you put the pad of the index finger on the trigger (the portion under the finger nail) it is far easier to get a straight rearward pull.
Todd Jarret has a good video on YouTube that explains all of this plus a BUNCH more.
Well worth the time to watch.
Residue on the end of the barrel: Normal. That is nothing but powder residue. The amount will vary with the ammunition manufacturer (some are cleaner burning others are not). Just clean it off after each session and you will have no problems.
Differences in group size: After a good 1911 trigger, any of the striker fired guns will be "less than pleasing". You start to get used to the 1911 trigger and subconsciously expect the trigger to break before it does with the striker fired gun. If you shoot - only - striker fired guns you adjust to their characteristics and your group sizes come back down.
I put together a web page on Shooting a Handgun
that includes the Todd Jarret link and some pictures I found/modified that may be of use.
Wear pattern: I think what you are seeing is more powder residue than actual wear. Make sure you - do - put a little oil on the locking lugs. Emphasize - little. If you have the more less standard oil bottle, the drops are HUGE. In that case put a drop or two in a Q-tip and oil the lugs with the Q-tip.
Yes Grasshopper, you are now HOOKED. Your 1911 addiction has started.