HPS40 charger & batteries

I recently acquired a HPS40 scope.

Should I remove alkaline batteries if I use the ac charger to power the scope?

If I use charger with NiCad/NiMh batteries installed, can I use scope and charge simultaneously?

BTW, I intend to use a 120vac (US) adapter that produces a regulated 12vdc that is good for 800ma.

Thanks all.