Just upgraded my speakers - do I still need the subs

Yes

Yes you will want to keep the subs imo. Unless you have dsp and crossover you would want to set the low pass on the subs as low as possible. 
 

If you have a good crossover time alignment that’s a different story. Cross them over at 60-70hz or so and play with it from there. 

Only you can answer your question.

Yes, keep the subs or get better ones. Subtraction is not going to equal better sound. I ran 4 much larger subs when I had my Ref 1s. Just make sure they are set up well.

I recently sold my KC62 sub because it was adding too much bass in my space. I went from LS50 Meta to Magnepan LRS+ to Magnepan Mini and all used the KC62. The KC62 was good with the first 2 in a bigger room. The Mini is in an open-ish space, different from the other 2, but the KC62 was too powerful in this new space. Though I think using my CODA #16 amp and the imersiv D-1 DAC with the Magnepan Mini was also too much bass. I replaced the CODA #16 with a Class D Audio GanFet 6.5 amp and the imersiv D-1 with a RME DAC and the bass is much lower. 

So, I think it depends on your room and amp. I would try the Ref 1 Meta without the sub and see if you find it lacking. Then sell it if it is not lacking. I always considered the LS50 Meta + KC62 similar power wise to the Ref 1 Meta. The Ref 1 Meta + 2  KC62 seems like a hypothetical Ref 2 Meta.