I think Doug T would be best able to answer this but I'll give it my best:
You will need a small mixer, at a minimum 3 inputs that can accept mic and line level and have phantom power. Perhaps a Sound Devices 302: 302 Compact Production Mixer | Sound Devices, LLC
Or a Shure FP33: Shure - Mixers and DSP - FP33 3-Channel Stereo Mixer
There are others available.
You will need a good pair of headphones. Expect to pay a bare minimum of $100.00 for a pair. The Sony MDR V6's are quite popular, but need a bit of TLC. I would not mix records on them, but they are adequate for your needs. Keep them dry and take care of the cable, they should last.
You will want a decent fishpole boom with a decent shockmount for the shotgun mic.
You will need a decent shotgun. You could use a Sennheiser MK66 w/ a K6 power module. Actually, the K6 module will also power some of the Sennheiser lavalier mics. Talk to a dealer
You will need at least 2 lavaliers. Either the Sennheiser (above) or Sony ECM 77's which are small, durable and good for speech.
You will need some carrying bags, velcro ties, appropriate cabling, gaffer tape, sharpies, waterproofing and labeling tape. You will also need ways to attach mics to clothing and/or skin or hair.
Schoeps mics are great to have,but most efp/eng work does not require them. You will most likely need to get some wireless gear before you need to buy Schoeps mics. I would seriously consider the Lectrosonics mics for wireless.
Contact a pro audio dealer, as opposed to a music/prosumer dealer.
I like Dale Audio in New York. B&H have decent prices but are not very knowledgeable about your particular needs.