So does that mean that the V1, V2 speeds, etc ,displayed on the ASI in the PFD will be different every time we take off..?
Yep, they are !
is it easy to maintain DME arcs manually at jet speeds during instrument approaches..??
Bear in mind that a DME arc is nothing more than a simple turn made to keep a constant distance from a navaid while flying around it and conducted at low angles of bank: a very simple manoeuvre in itself and couldn't be any easier by using RMI ... though, the higher the aircraft speed the faster should be your response to keep distance constant.
If you are asked to conduct a visual approach during the day without the ILS, i believe that your judgement cannot be less than perfect. True?
There're different types of approach you may conduct under IFR beyond ILS: eg. IGS, LOC, VOR, LCTR, RNAV etc. If you're circling or just asked ATC for a visual, the landing runway must be in sight and must remain as such throughout the entire manoeuvre. Your judgement on either the horizontal or vertical path is often improved by using AFDS functions like FPV (Flight Path Vector) and visual guidance systems like PAPI, VASI, LDIN lights etc. A jet aircraft has a relatively low response time on thrust changes and its handling characteristics are different from situation to situation: basically, it's a bit trickier to fly a jet than a piston/props.
Hope that helps,
fredgrav