I refrain from ordering from Amsterdam. The US gets a very small amount of mail from there on a daily basis as opossed to England and the packages are more likely to draw suspicion.
Amazon is awesome!! I buy all my nutes from a seller called Hydroponics Market. Their prices are great, everything is free shipping and it gets to me in 3-4 days.
I believe flushing does help make a more quality smoke but I dont think the difference is enough to justify changing out all my buckets. I gave up on flushing when I switched to hydro.
A hundred hours is about 100 hours longer than I have seen from alot of people here. I really suggest that you pick an easy to grow strain, go easy on the nutes and try to go a bit smaller than you are planning. People think it is easy to manage a big grow. It is alot of work to do it all...
The proper information and knowledge is far more helpful for a succesful grow than all the equipment in the world. Trying to go big right from the start is gonna leave you quite disappointed in the end my friend.