Enjoy yourself OP!
We've had a Hymer for about 7 years. Some things I'd say:
Get very familiar with how your water system works. DH has spent a lot of time ferreting around in the water tank reconnecting pipes and replacing pumps 
If you're going to travel in winter, check whether your motorhome discharges the onboard water to prevent freezing (ours does). Take cat litter for emergency grip, and snow chains of course.
Maybe get a Schengen calculator app on your phone to make sure you don't breach the 90 in 180 days rule. The long term stay (6 months) visas you can get relate to individual countries. I've got French 6 months visas 3 times, and there's a lot of paperwork and it's time consuming, but it's straightforward and there are FB groups to help (obviously you won't need external help for Spain!).
Certainly in France, almost all towns, and many villages will have aires, some with hook up, almost all with grey water drain, water refill and loo emptying facilities. Switzerland is great too, in fact that's my favourite place to motorhome.
https://park4night.com/en/search is a really useful site to look at. You can subscribe for next to nothing for extra info.
https://www.campingcarpark.com/en_GB is this, and growing - you pay for a card, and can reserve overnight spots on sites across Europe.
https://www.caravanclub.co.uk/uk-holidays/uk-sites/certificated-locations/ is another useful site (UK). If you sign up, you can stop on small (only 5 caravans/motorhomes) certified sites in the UK. Often it's farmers fields, with a loo and maybe a shower. We've stayed in some wonderful places.
https://www.vicarious-shop.com/products/all-the-aires-france-2025-10th-edition actual paper so a bit old school, but you can buy map books for Europe here, with aires marked.
Re bikes, we dont take them with us (DH has an injury that makes cycling difficult). I'd say that has affected our enjoyment a bit tbh. Motorhomes are such big beasts that taking them into the centre of small towns, and even larger towns with old centres, is stressful, and sometimes impossible. Being able to bike into towns and villages is really handy.
Hope some of the above is useful, and apologies if you're already aware of everything - these are just all the things I wish I'd know at the beginning. Have a wonderful adventure.
Oh and remember to wave to every other motorhome!