QTR-Quadtone RIP

Hello,
I am new to this group and brand new to the Quadtone Rip.  I have been
printing with the Epson 3800 for about 4 months using the AWB driver for
B&W prints and using Eric Chan's profiles for Epson Exhibition Fiber
paper primarily.  I really love this paper but it only comes in sheet
and not roll.

Here is my problem (followed by my question below).  I am printing
panoramic images form scanned NOBLEX 120 6x12 negatives.  I have been
printing panoramics 16.5 x 39 inches on 2 sheets of 17x22 Epson paper
and planning to join them together when mounting to board --- not easy
to get a perfect join and have minimally visible seam.  My understanding
of the Epson 3800 has been that I can only print a maximum length of 37
inches without a RIP.  Regardless, since my largest sheet paper is 24x30
( I can cut to 17x30) I still need roll paper and will want to print
images even longer than 39" on a single sheet in the future with
digitally stitched panoramics.

Here are my questions:
1. Can anyone tell me the maximum length I can print using the Quadtone
RIP? And if there is any special information I needed to know about
using the software to use it effectively for print length beyond what is
written on the PDF from the website?

2. I am planning to use Museo Silver Rag for gloss surface and Canson
Rives BFK for matte surface. (I also plan check out Harmon Gloss FB AI
paper as well).  Is it best to use the paper profiles from manufacturer.
Eric Chan's AWB profiles? or a Quadtone RIP profile included in software
for B&W.  I do not intend to build my own paper profiles.
I ask because surprisingly I found that when I used the Museo Silver Rag
AWB profile by Eric Chan on the Museo Paper paper, my print came out too
light and with different contrast compared to the perfect print from the
Epson AWB profile for Epson paper. When I did another print on Museo
Silver Rag with the Epson AWB profile it printed almost exactly as my
Epson Paper/Epson profile print, except for the difference in paper base
colors.

Many thanks,

Bob Parker