If you are gonna shoot skeet, get the skeet choke. Most clubs require this anyway. Later, when you get to the hunting, get a mod, or full choke.
The Sigma is an under rated gun. If you ever want to lighten the trigger squeeze, it is very easy to do. You can find instructions on numerous gun forums. I'll let others comment on the 9mm ammo.
In UK we are restricted to long barrels I find they will target an intruder as fast as any bird. Save yourself some money and for self defence sleep well in the knowledge. You can nail the low life intruders from greater distance.
Here in the states home defense is usually close quarters. Plus the shorter barrels will allow the user to get through narrow halways & tight corners easily.
A Modified Choke Tube is a good universal choke to use.
As far as cleaning kits get a universal kit from Wal*Mart.
I don't think they combine long gun & handgun kits together, but they might.
If they don't look for a long gun kit then just buy the individual 9mm brush, cloth holding attachment, etc. That way when cleaning the 9mm you can use just the section of the rod with the handle and attach the 9mm cleaning pieces to it. When cleaning the shotgun you will use all 3 sections of the cleaning rod with the appropriate attachments from the kit.
I'm getting very anxious because my FOID card should be arriving shortly. I already have my order saved at budsgunshop.com, so all I need to do is check out. I have a bunch of questions regarding purchasing the guns online.
1) Can I order now, and pickup the guns after my FOID card comes to speed things up a little?
2) Do I just call all the gun shops in my area and ask what their transfer fees are to find the best prices, and are there any other questions I should ask? Do big stores like Bass Pro Shops usually have lower fees then the smaller shops?
3) Should I plan on fees for each gun, or is it only one fee if I buy both guns at the same time and have them shipped together?
4) Do I need to inform the local gun shop I'm having it shipped there before I place the order?
5) Do I still need to go through the waiting period once it arrives, or can I pick it up as soon as it gets there?
6) Am I missing anything that I should know?
Thank you all for the help I've gotten here. I really don't know what I would do without it!