What I know to be true about DMP is that most CCCs add a TL the account is being managed through one. Also most CCCs close the account after it is PIF and it showas up as account closed by grantor. Most CCCs will lower interest rates and the standard now seems to be around 10%.
National City gave me a mortgage early on DMP at a rate of 7.25 which was more to do with my low scores caused by very high CCC util and 2 recent 30 day lates caused by my transition into the DMP paying the CCC rather then me.
Last November National City gave my a Visa card with 0% BT for 15 months, 10k CL and and 13% rate which was they best I ever had.
SSFCU just gave me an autoloan for 28k at 5.4 60 months which is their best posted rate.
While I was in DMP, Sams gave me a 300 CL Sams card which now is at 3100 CL after 4 years.
I was also UD'd by AE when I entered the DMP.
You dont have to add all your CC to the program and I would try to keep the oldest account out of it. I did that with my Cheveron card. For some reason I didnt add it but I dont remeber why. It probably was out of good luck I suppose.
I do not know if any of the companies I had products in DMP with will give me a CC or not. My reason for posting the detailed info about credit I got while I was in DMP and after was to show that there is life after DMP and while some companies might reject someone because of it, others will grant them new credit at rates reflective of how they are manging their credit now.
1/25/2021: FICO 850 EQ 848 TU 847 EX