Don't know about the weight, but most post 2008 cars came fitted with the upgraded 210bhp engine which is both better out of the box and responds better to remapping. Also interiors of facelifted cars are nicer.
Mine is a 2007 so the older 200 bhp unit. So far I have added:
OMP strut brace
Some pictures on my profile page I think if you want to have a gander.
I am planning to finish off with exhaust, koni dampers and 15mm spacers when I finally get round to it.
Having spent quite a bit on the car, with hindsight if starting again I would do the following in this order:
1) Fit OMP strut brace. Most cost effective mod I have ever bought. Greatly reduces flex and makes car feel more composed.
2) Fit Eibach 30mm springs and Koni dampers. I fitted the Eibachs by themselves and the ride quality has deteriorated gradually so that whilst she now handles well, the ride is very firm and is starting to do my head in.
Fitting is about £400 if fitting both shocks and springs at same time, or £400 a time if having the shocks and springs done separately. Wish I had done both together now!
3) Remap - a good remap is essential to get some decent power. Gus at Alfatune did mine. First map was a bit too aggressive for me so he kindly adjusted it a few months later free of charge and car feels better now, if not quite as powerful on the road. Still bags more power than standard and much less lag. Better MPG too. My car is a bit smoky now, but apparently the later 210 bhp units respond better to being remapped and produce less smoke.
4) Clutch - expect to replace your clutch and possibly your DMF. Both times I have had diesel Alfa's remapped or fitted boxes, the clutches have given up soon after. In the case of the Spider, the DMF needed doing too. I bought a standard clutch then sent it to these guy to be reinforced with kevlar plating:
Clutch Specialists Manufacturer and Supplier of Handmade Clutch Kits
Done about 15k miles on my reinforced clutch now and no issues and just as light as standard unit. Time will tell I guess.
With these done you should have a pretty sorted car that will go and handle. Brakes are simply awesome out of the box. You might want to fit some Ferrodo pads once the OEM ones get worn, but otherwise the standard ones should stop you in all conditions with no bother.
Hope this helps and good luck. I was disappointed with my Spider when I bought it as it handled like **** and the old 200bhp engine is ridiculously laggy as standard, but with a few mods done it is now a pretty good car and turns heads more than anything else I have owned, whilst getting positive comments from friends, family and clients.