Cambelt is essential to be changed every 36k or 3 years, whichever is sooner. The consequences of not doing it will be a snapped cambelt, resulting in bent valves, cracked valve guides, damaged pistons, bottom end damage, ususally works out around £1500 to get the engine rebuilt.
Check the oil weekly, these engines burn oil as part of their combustion process, anything upto 1 litre per 1000km, although the norm is much less and some hardly burn any at all. It needs to be topped up regularly, failure to do so will result in the engine running low on oil, and the bottom end will start to knock (usually number 3), meaning a new set of shells (£100+). Don't replace the shells quick enough and it'll ruin the crankshaft, and possibly throw a con-rod through the block. New engine time. Don't wait for the low oil pressure light on the dash, this may as well be a big £ sign as if you see this light the damage is probably already done. Daft design, I know, but this is the way it is..
However - you have just bought one of the best 4 cylinder engines around, for feel, response, performance, sound, not much without more cylinders comes close, you just have to take good care of her. Don't rag her til she's warm, check the oil weekly and top up when necessary, follow the cambelt schedule and you'll have no worries.
Oil to use is Selenia 10W40 Semi synth. Although any 10W40 fully synth will do just as well, I'd advise changing the oil and oil filter every 6 months or 7k miles, whichever comes first.
Welcome to AlfaOwner