It is not "necessary." They are both very good additions to any home-brewery. If you have one keggle, then you'll probably have three one day. If you have three keggles then you'll probably get a pump. If you have a pump then you need a hop strainer so you don't clog your pump when you pump your wort out of your keggle.
When I started brewing, I used two buckets (With blankets for insulation) for a MLT, and one large canner pot for my HLT and BK. It's the only equipment you need that's "necessary." But if you start doing 10 gallon batches, or you want to eliminate boilovers, or just wanna expand your brewery; those are two outstanding additions.
Awesome Catt. I hope you enjoy your additions!