Michael , a slight correction on your point (5) if I may.There is a limit depending on which unit you have. See below for the Nuvi250
I don't know if Dave noticed that I attached the pdf user manual file in my previous post to help. ( #18)
Dave, Dude!!!! (did you have a slight sense of humour failure amigo?? !!)

I hope I did not upset you- apology if I did-
To add value to your Michaels' post and to help you to keep costs down:
- Keep your Nuvi 250
- Make as many routes as you like BUT with
no more than 200 waypoints each.
That is your units limitation and I find it best to always go a bit less than maximum.
- buy an external memory card or two- it is always a good idea to have a copy of important data and cards can fail.
- Create a folder called Garmin and a sub folder to that called GPX on these cards.
- From Basecamp, save your routes file or files in .gpx format and put these on your external memory card.
Your limit is the maximum card size your Nuvi is able to read. Do your homework.
Store as much as you can on the external memory card.
Name your routes with something that is easy to understand. for example
'London Victoria-TO-Dover'
For Waypoints:
You have choices- IF you wish to have different icons to display on your screen for different categories (pictures are better than text)- it means more work and the creation of .csv and .bmp format files ( see below how to)
OR, if icons are not important to you, then just save the file in .gpx format as well
Create as many as you like in your planning from home, save that file in .gdb3 format then convert it to a .csv file.
This file will need a corresponding file which is a .bmp file ( with the same name) and you use POI loader to send it to your unit.
The .bmp or bitmap is the icon which will display on your screen.
If you have different types of waypoints then each will need a separate file sith its matching icon if you want different icons to display.
All the files MUST be grouped in one single folder for upload to Nuvi using poi loader. Each upload erases the previous data on the satnav. Fir good practice, I use the 'remove' option in POI Loader before each fresh upload.
Doing the above will not use any of the units 500 maximum waypoints which you can then create and delete / or edit via the Nuvi on your travels logging points you wish to keep. A useful tip is to creaste one called 001 for where you park your bike- deleting as you move off again- it prevents you forgetting where you are staying/or have left your bike... don't ask how I know that
To give you a comparison, my unit can hold 4000 waypoints in its memory, but thanks to POI Loader, I have over a quarter of a million of them in my unit.
The gpx format files and the .csv ones cannot be edited on the unit and require a computer .
Total expenditure = 2 or more memory cards only
Investment in learning 'how to' time , lots!
Free software needed:
- Garmin Basecamp
- Garmin POI Loader
- GPS Babel for file conversions
Windows 'Paint' or the like photo editing software to make icons
Have fun