you definitely need time for this trip. More Time = More Fun = More Adventure
To the Roads: In Poland some of them were not so good. In Skandinavia you have the choice: Either you drive the hole time on normal street or on gravel roads
How you like ...
At the Baltic states you can eat out in restaurants because its cheap and tasty. But in Skandinavia its quite expensive! Especially in Norway. Gas over 2€/L and food was very expensive - even in the supermarket! The "rema 1000" supermarket was the cheapest one. But if you want to go to a restaurant its heavy, for example: one pizza for ONLY 20€ :( In Finnland you have to go to the ABC Gasstation. Sounds strange but eating there is cheap and tasty - all you can eat buffet for 9,60€ :)
Camping was great. Good Tent = dry = happy :) campingprices between 9€ (Poland) an 30€ for 2people with one tent. If you stay longer there buy the campingcard:) wildcamping = no shower only cold rivers and lakes :) but definitely possible and no problem.
You need a kredit card, very important! helpful for some gasstations...
I hope we could help you. If you have more questions or need some more tipps, give it here! :)