I am in India... Those are the prices I am offered by local Epson, Canon Dealers. Aren't they reasonable?
I'm always surprised by how different pricing is outside of the US! 8300s can be found for ~$3000 here.
...the positives are used for making screens for my large format screen press.
Oh how fun. I've been making digital negative and positives for alt-processes myself since 1991 and teach workshops internationally on this, so this is a fun topic for me. If you haven't already, see my article on "Using i1Profiler for QTR grayscale measurement and profiling" at http://www.on-sight.com/2012/04/11/using-i1profiler-for-qtr-grayscale-measurement-and-profiling/
Software: Quadtone. If no good found MultiRip, mostly.
QTR RIP only works with some Epson printers. IMO, you can make fantastic calibrated negatives and positives for any process with any printer using the regular driver. There's also some new software for this process that will be out soon. Can talk about that just yet. Long story short - you've got options and can make your positives on any printer.
Also, if you're going to be printing from Photoshop consider the streamlined workflow that Canon's Photoshop printing plug-in provides, and the on-printer print storage option. Some users really find a lot of benefit in these, while other's don't - all depends on your workflow.
2. Which one is Latex printing, nether Epson nor Canon. Which brand?
HP's latex printer are becoming more and more popular in high volume canvas printing facilities. They surface of these prints looks great and they don't require varnishing like pigment prints. A lot of my larger clients have migrated to these printers and are seeing increased profits from doing so. The initial up-front cost is higher of course which makes it hard to justify for lower volume users.
If you're in signage you should really consider the UV Curable and Eco-Solvent printers that dominate the signage printing.