I don't have first hand experience of the sites, but having done a bit of looking into them it seems that they may not yield too many great delights.
The one that I found most on was Forum Hadriani
"Today, a beautiful model of the ancient town can be admired in the small but nice Museum Swaensteyn in Voorburg. One of the houses of Forum Hadriani has been reconstructed at the Archeon archaeological park at Alphen aan den Rijn. The remains of the ancient town are one of the monuments on the UNESCO list of world heritage.
[sic] They are not visible; the modern park Arentsburg, near the Mariannelaan, occupies the site."
It is only in Dutch I'm afraid but this
site has some up to date pictures of the dig at the site.
A Google Image search reveals four reconstructed posts in what looks like a car park!
From the list of sites that you put in your post this is the most substantial remains I have come across so far
Hopefully those with local knowledge can shed some more light on them.
To give a perspective of someone who has visited the Netherlands and focused on their WHS, don't make these sites the sole basis of your trip. If you do you will miss big chunks of the country that may actually be of some interest to you.
If I were being brutal I would only recommend a visit to the Rietveld Schroderhuis (you will need to book in advance, if you haven't already) and Kinderdijk as this is a good stereotypical Dutch scene.
The four other sites associated with Water management can easily be seen in a one-day round-trip in a hire car from Amsterdam. A fair few of the sites on the tentative list can be added to the list as they are on the route, but on the whole these are not must see sights.
The only real plus point I could say on visiting these sites was that you got away from touristy zones and got to see something of everyday Dutch life.
The Netherlands is a nice country to visit, it is easy to get around and the population is very welcoming and friendly. Unfortunately the country's inscriptions on the World Heritage List and it's tentative sites don't pick out the highlights (Amsterdam and Reitveld Schroderhuis excluded).
Anyway, enjoy the trip