Changing to 18" from 17" rims, issues?

[UppNer]

Hi all,

I have a 986 -00 base with 17" rims today.
Yesterday I bought 18" 997 rims which I guess (hope) will fit my car.

But, how will I for sure know that they´ll fit my car, is there somekind of table or calculator that can tell me this?
Do I maybe need spacers or do some other mods?

The new rims are - Front: 8Jx18H2 ET 57 and Back: 10Jx18H2-ET58

Is this enough information or do I need more?

I mean, just because they fit in the wheelhouse standing still, what happens when I start to drive on a bumpy road, in corners etc?

How shall I think?

Thankful for all input on this, BIG thanks in advance!