Sump plug for mine was a 13mm hex socket. which was knackered and I changed to a square hole type. (see my "sump plug replacement" thread on here) its on bottom drivers side of sump between the chassis with no room to get a socket over it.
Oil filter is between bulkhead and behind engine halfway up on drivers side again (if uk car) you can just reach it from above but easyer from bottom up from the sump.
I did the oil cartridge filter by hand (if your tuff)
Oil 5W-40 Fully Syth Halfords own £35
Alfa Oil filter Cartridge Ebay £6
sump plug halfords £2.99.
MaxiScan MS509 £47.00 on Ebay to reset and test ECU.
Got quoted £185+vat for Oil/ filter change with a ECU reset!!
20k is to long for me too guiness change the oil every 10k. like stibbs said it does mix with fuel and soot, when i changed mine before 10k i had and extra litre of oil/soot/fuel come out then what i put in (4.6litres fully Synthetic).
The fact that your oil mixes with all the soot and unburnt fuel builds up the oil (and pressure) and running round in your car with over a litre more oil then recommended is asking for trouble. its a terrible idea and one which has made me regret switching to diesel from petrol.
118k on my car and its fantastic still like new but only ever had EGR and DPF issues.
it does spoil the reliabilty of not only alfa diesels but almost every other make which all suffer from this
half baked idea!
my mates just bought a brand new Oct VRs he loves it, cant wait to show him what you boys have said