Is this sort of thing frowned upon?
		
 
		
	 
 
I have a fairly big saddle bag, can easily take a jar of jam.
I've never had any comments 

Racers dont have saddle bags because they have support cars with all the stuff they could possibly need following them! Every little helps in the world of racing. But in the 'real world', If someone is that anal about weight that they wont carry a saddlebag with must haves in, then they've got something wrong with their head! Especially if your commuting on the bike! You're going to have to carry a bloody heavy lock as it is, whats another hundred grams?
/rant over
 
For what its worth I carry an inner tube, 2 tire leavers, multitool, asthma pump, antihistamine syrup (I have a very bad milk allergy, even if I accidentally eat half a crisp with milk in without knowing I go into exercise induced anaphylaxis!) 3 AAA batteries, a few sweets to cheer me up and usually my mobile.
 
As for the rest of your questions:
Drinks, most have two bottles as others have explained.
Jerseys have 3 pockets in the back which carry decent amounts, I sometimes put a drink in there.
 
Get a saddle bag for supplies. I hate having to wear my rucksack all the time when cycling.
 
I got my roadie in September, I started off wearing a t-shirt and my baggy basketball shorts. I too said I'd never wear lyrca!
I then got a cheap aldi jersey, had enough of it looking rubbish.
Im now wearing specialized bib tights, gloves, jersey and decent cycling shoes.
Wear whatever your happy in, if thats baggy shorts then go for it!
You'll soon be making your way to the lycra anyway 
 
Why do I like road bikes? I like bikes in general. But road biking/track racing just seems to be my thing. Simple as that! I ride to uni on mine and yes, I do get a mouth full of fumes every now and then but its really not that bad. But thats not the end of the story, just because its a road bike doesn't mean you're stuck to busy roads!
In summer Im going to ride around Anglesey and snowdonia, surely thats just as good at getting me out doors as mountain biking is!
 
Club runs are something Im still pretty apprehensive about. 16mph isn't to hard to average if your in a large group though! You'll be surprised how quickly your average increases.
 
Final word, get a road bike. Get out on the country lanes with it. Go a little to fast down them hills and scare your self. Push your self a little bit harder than you should doing that hill climb.
You'll soon figure out why road biking is great fun!