1) Probably repairable, depends on your exhaust shop. I've replaced all three cans on my exhaust system over time by cutting out the old ones and replacing with new units. Naturally, your mileage may vary.
2) If you're talking about the actual plastic connector that holds the contact sleeves, you'll be lucky if you can find a replacement. Try your dealer. otherwise, replace the connectors with aftermarket sleeves.
3) No idea. Have monster third party stereo in mine
4) You can get a new tube from your parts shop or dealer. Your first port of call should be Fastlane, who host this forum. If, like me, you live outside the US and cannot take advantage of their services, you can at least try to find the part number there.
5) Don't know about this, certainly doesn't happen on mine. Maybe its blowback from the rocker cover, which means you've got some sort of non-standard pressure going on in there, which may well be linked to...
6) Seems like a lot of oil is being used somewhere, my engine has 170,000 kms on it, which admittedly is a lot less than yours, but uses no oil between changes every 5,000 kms. If its not being burned in combustion, and doesn't appear to be leaking, maybe its blowing out somewhere. Check more thoroughly for leaks, esp in the engine compartment.
7) Have you checked your spark plugs recently? They might need cleaning or replacing, and don't use platinum, stick with the recommended type. You should also check the fuel filter, if its clogged it can cause this behaviour, and based on my own experience I'd take it off and check if there's water in there. You might also want to clean the inlet lines to the fuel distributor, try a search in this forum. I sure hope its one of those things, elsewhere lies madness and desperation while you try to get the fuel injection system back on track. Before you do anything with the fuel system, check all the hoses for brittleness and leaks. If the breather hose is broken, chances are the rest are in need of attention.
you should do a search on a lot of this stuff, there's plenty of help and advice lurking in the archives.
good luck