No need to drain oil or remove plugs. It's only a half hour job once you've done it once, have you got a haynes manual - I'd recommend following that the first time you do it.
This is what I do in the form of steps. I'm sure someone with more knowledge, pics and a better way with words will input more.
I'd also recommend just installing the inlet cam first, the 1.3 exhaust cam changes the powerband quite a bit, not necessarily for the better, especially as yours is auto.
1. Buy Cams.
2. Unplug leads, unclip hoses from rocker cover.
3. Unscrew rocker cover.
4. Remove rocker cover and rubber gasket.
5. Set engine to TDC. (not necessary, but makes it easier)
6. Make markings on the sprokets and chain to note their position.
7. Remove sprocket bolt and washer from one cam.
6. Remove sprocket from cam and chain.
7. Remove camshaft retaining bolts and retainers(?)
(keep all bolts with thier respective holder to fit back in same location)
8. Remove Camshaft.
9. Place 1.3 Camshaft. (the one with the slot on the end is the exhaust cam, for the distributor)
10. Bolt the cam down with correct holders and bolts in same location. Torqued to 22 IIRC
11. Refit sprocket onto camshaft, dowel and chain with all markings realigned.
12. Refit sprocket bolt and washer torqued to 115 IIRC.
13. Either do the the other cam or refit rocker cover and gasket and put back leads.
That's the essentials anyway. And as you can see it's pretty straight forward. So go get some cams.
