normally you wont notice any difference in driving perfomance when a regen takes place. There is no dash indication, the only way to reliably know is by having the current mpg displaying, it will take a sharp drop when a regen is underway (my 1.9 goes from average 35-45 down to around 20 mpg when it regens in normal driving i.e. during normal cruising)
if you do notice it is regening and you are at the end of your journey then i guess i would probably drive around the block for a few minutes until it was finished - usually seems to go for 5-10 mins max.
I can honestly say (touch wood) in 11k miles i've never had a dpf issue or really noticed it other than the mpg indication.
For the remap i believe they ensure that at the point in the rpm range where the emissions is tested it runs sufficently clean to pass. There is a remap that disables the sensors for it and also for the egr which is switched off closed so no errors are triggered. Wish i had £700 spare to do it.