Fluid bolus?

Pump for accuracy. My background is Peds so there is almost never a case where you use a full bag of fluid. 

It depends. Are you giving a bolus on someone who's dry and just needs fluids or is this an unstable patient in shock? Fluid resuscitation is an imperfect science and can be risky so you have to take the entire clinical picture into consideration - slamming 300 cc/min into some patients could throw them into cardiovascular collapse before you have a chance to realize what's happening and leave you worse off.

A pressure bag will give you a better flow in an emergency but in my experience the pump is enough for the majority of situations.

As MaxAttack mentioned, most of the time a fluid bolus by pump, ours goes to 999mL/hr, will be sufficient in my experience. If you have access to a rapid infuser I imagine that would give you the accuracy of a pump and the capability of faster infusions. I haven't used one, however, because no one could find it when we recently needed one. 

Depends on why you're giving. If for shock with Sepsis or hypovolemia a pressure bag is the way to go. When you need it in really fast, even @999cc/hr which is the fastest most pumps will go, it will take an hour just to get 1 liter in.

It honestly all depends on the IV access you have.  If you have a large IV like a Cordis Introducer or something very large like a 9Fr or 11Fr central line you will be able to bolus fluids much much more quickly than setting a pump to 999

Again, it depends on why you are giving the IV fluid bolus. Our Sepsis protocols orders the first of four liters of IV fluids to be delivered over  15 minutes, which is 4,000cc/hr.

I second the pressure bag when you’re giving it for volume or sepsis. You can give a bolus on a pressure bag pretty quickly even into a 20g IV. But I also second the need to consider the patient. If you have a cardiac patient, history of CHF, kidney disease, etc, check on that rate and total for sure. If your patient is losing volume in front of you due to bleeding or vascular leak in the case of septic shock, they need the volume ASAP, a pump will not do.