The problem is the Batis 25 and 85 are really hard to get at the moment but I would start with the 55 as folks just love that lens and it can be your shorter 85 if need be with crop mode.
The one question I always ask folks is which lens are you more likely to have has the lens cap lens. Always on and gets a great percentage of use. Most people its a 50 and for me its a 35. So once you know that than you can gap for each lens
Lets say its 35mm than 15, 25, 35, 85
If its was a 50 than a good gap is 21,28,50, 85/90 and than something longer on both
If your just getting into the system and want to keep costs down. Than the 28 F2 is really cheap and quite good and than the 55 and if your into Macro the 90 is very good. The good news you can buy all three today and not wait
If money is not the biggest issue and very high quality than yea the 25,35 and 85 are about some of the best you can buy in native glass along with the 55.
Now if you like manual only lenses but still native the Loxia 35 and 50 are very very nice and you can find them today in stock.
But you need to figure out that lens cap lens as that is the key to a complete system. I always say think system purchase not as individual pieces because than you wind up having to sell something later to get your gapping correctly
Zooms the 16-35 is very nice but from 16 to about 26mm than its starts to lose quality
BTW don't ever be afraid to ask those newbie questions. Please this is how you learn and most folks here love to help.
Oh and if you need a body . I think the folks at Newtonville in MA have one in stock. The A7rII, tell them I sent you