First up most of
GW's tools are pretty good to high standard - they might be overpriced compared to other options, but they are solid tools so don't worry about choosing to use them. Those suggestion not to use them typically (in fact with the exception of the pin-vice as noted above) only talking in terms of value for money compared to other choices.
These are basically identical to the ones
GW used to sell before the black ones. Great little clippers
Pin Vice:
There are loads on the market and your standard silver metal simplistic pin-vice is pretty good. I would suggest that you want a pin vice that can take up to a 3mm drill bit (which is about the limit for most - note sometimes they will have two slot holders within them so many times the cap end will unscrew to access that).
Green-stuff tools:
I 100% second the suggestion to get both the standard metal tool (as shown on
GW website) and the colour-shapers/clayshapers. You can also hunt around on ebay and the like for clay sculpting tools and you can get a variety of styles and types (though the standard one is good enough for a wide range of uses).
Clayshapers/colourshapers (same thing different product name) are basically like a paintbrush, but with a silicone head. You can often get them in a pack of 5 with 5 different heads. They are fantastic for working with greenstuff since whilst the metal tool is good for packing and moving it around; it will leave a raised edge. This edge requires filing/sanding down once the greenstuff is fully cured (that can take 24 hours or so).
Colourshapers work by letting you rub over the greenstuff with pressure and will smooth out those edge regions. It's much like using your finger, only you won't have to deal with fingerprints; and the tip is much thinner so it can get into a lot of tight spots. It takes a lot of work out of greenstuff working.
They come in three hardness from white (soft) to black (hard) and in theory you work black to grey to white to get the smoothest edge.
Note when working with greenstuff you want to keep a little container of water nearby. Regularly dip your tools in the water to avoid them getting stuck to the greenstuff (greenstuff is somewhat sticky until it cures). You can also use vegitable oil which will remain non-sticky for a lot longer; but you will have to wash the model (warm water and a tiny bit of soap and an old tooth brush - identical method to resin cleaning) to remove the residue once the greenstuff is fully cured (otherwise paint will have trouble affixing to any oil coated areas).
As for a cutter/mould line remover some people swear by mould line removers; others use a scalpel blade very carefully scraping at the line. The weakness of a blade is that if you don't get the angle right you can cut lines into the model if you scrape badly. I've never used a mould line remover, though that would be the one bonus of them - though I'd still expect a blade would be of use to get bits out of tiny cracks and a general scalpel is good for a wide variety of general scraping/cutting/slicing uses.
I'm actually rather fond of
GW's blade as it comes with a larger handle which is well suited to holding it in the hand close to a model; whilst many standard scalpel blades are thinner and more "pen like" but they are still easily usable.
In the
UK you can get Swann and Morton scalpels for less if you get the non-sterilized versions (as you're not doing medical work you don't need sterile tools). An ACM No 2 handle with ACM No. 2 blade is a good standard setup and the blade takes in and out like hte
GW one with a screw (as opposed to the clip on types that can be more fiddly). If you get off ebay or hobby stores you can likely pick up a packet of 5 or 10 or so blades (they will go blunt over time so having spares is good)
ACM2
6000 pts - Harlies: 1000 pts - 
4000 pts - 
1000 pts - 
1000 pts 
