I've done a Hook of Holland to Amsterdam ride three times in the last couple of years. Great fun, lovely people, and a cycle path network to die for. If you want a brief introduction to the paths, look at the Holland section of this site...
http://www.cycletourer.co.uk/cycletouring/holland.shtml
The cycle paths have numbered marker signs along the way and at every junction. At each marker, they indicate the direction to the next marker. If you know the sequence of numbers along your route, you don't really need maps and certainly not GPS gizmos. The cycletourer website provides a link to
www.fietsersbond.net
The site is in Dutch but do not despair...cycletourer gives you hints on how to use it. The great thing is that you can zoom in on the maps so that you get street by street maps of the route in the towns and cities. Out in the country, you are unlikely to get lost, but it's quite easy to miss a marker sign in the towns.
For general route planning, I found that the maps published by Falk are good. The scale is 1cm=500 metres. This series shows the long distance paths "Fietskaart met Knooppuntennetwerk". You should get numbers 14 and 13 if you want to stick to the coast before turning right towards Amsterdam. There are a whole load of other maps in the same series if you want to try another route. I went Hook van Holland, Monster, Scheveningen, Katwijk, Noordwijk aan Zee, Zandvoort, Haarlem, Amsterdam.
A really good place to get your maps is this website ( get a decent street map of Amsterdam here too)
http://nieuw.dezwerver.nl/
Don't worry that it's Dutch, just pick up the phone and you will be guided through the buying process by delightful Dutch people.
A basic but very central hotel in Amsterdam is the van Onna. I think it's about 45 Euros a night which is very good value for Amsterdam. Book in advance because it gets full very quickly.
If you use the search function on CycleChat you may find a whole lot more information. By the way, the Stena overnight ferry from Harwich is great fun and not too expensive. Booked in advance with a bike and my own cabin in both directions it was £114 last September.
Have fun.