Are these actually safe for live electrical work?

Klein rates the two-layer insulation for protection up to 1000 V. That rating depends on the insulation staying intact, so inspect the grips before every use and replace the pliers if they are cut or worn.

How do these differ from standard long-nose pliers?

They are heavier, with longer handles for more leverage, and they add side cutting and stripping plus voltage-rated insulation. Standard long-nose pliers are lighter and slimmer but offer no electrical protection.

Can I use them instead of dedicated wire strippers?

For occasional stripping, yes. For repeated or precise stripping work, a dedicated stripper gives cleaner, faster results because the stripping function here is secondary.

What can the side cutter handle?

It is meant for wire and light cutting tasks typical of electrical work. Avoid hardened steel and thick cable, which can nick or damage the cutting edges.

Who should buy these over a cheaper pair?

Anyone working around energized circuits or cutting wire all day. The forged build, leverage and insulation are the reasons to pay more than for a basic long-nose plier.