Welcome, Holland!
Bike and Equipment:
1. I'm considering buying a used bike once I reached Netherlands. Must I have a touring bike or a city bike could work? I prefer coastal brake, do you think I could get away with only one gear? The country is said to be fairly flat except for two provinces: Overijssel and Limburg. Also, I prefer occassionally riding standing-up, I don't know if this is possible with full panniers.
You will ultimately be more comfortable, and able to enjoy your travels, if you ride a lighter bike with gears.
Also, while it's an extra cost and a little extra work to pack, unpack and repack, consider bringing your own bike. That way you will be familiar with it and comfortable on it.
Finally, think about taking your bike to a good LBS and getting a bike fit. Explain the kind of touring you want to do. Small adjustments can make a big difference in how good you feel at the end of the day, and how eager you are to jump back on the bike the next day.
4. I read that all restaurants carry bike repair kits throughout the country. What items do I need to keep in my personal repair kit anyway?
Tire tubes
Tire levers
A good multitool
Patch kit
Emergency ID/contact
Small bottle of chain/gear lubricant
Some type of bicycle pump, either attached to your frame or in your repair bag
On a ride of this sort you might want some sort of chair repair mechanism, although I don't know much about that. <--I'm sure someone else here does.
Even if every restaurant in the country has bike repair kits, if you are 10, 20 or 50 miles from the nearest restaurant, walking your bike there would be a bummer! Also, learn how to change your tire and practice a few times before you leave.
Luckily, there are all kinds of seat packs that fit nicely under your seat. It's not that much extra weight, and it's well worth it.
Have fun!
2001 Cannondale R500 <3
2011 Specialized Ruby Elite Apex
2021 Tangential Speedarama