Simple vs complex object and merging vs culling

Hi,

I'm working on a city scape with a details center and low-res surroundings (all houses).
So the houses in the center are detailled meshes (high vertex and poly counts - a least a hundreds) partly with interiors and all with multiple materials (at the moment).
The houses in the surrounding area are basically cubes or stacked cubes (very low vertex and poly count - most below 20) plus a few a little more complex. There are obviously more of these.

So I'm wondering what is smart concerning Draw Calls and Object Culling (frustum and perhaps optional occlusion culling too).

Am I correct in assuming:

- In a row of detailed houses I can better merge each house separately. That way I reduce Draw Calls because of all the separate objects in my house, but preserve a lot of culling because each house is separate.
- Instead of merging all the detailed houses in one row together to get the least Draw Calls, but that would hinder the culling dramatically
- With the low-res houses I can probably better merges these in groups (geographically speaking, say 8-10 zones moving around the center), this lowers the number of Draw Calls nicely but not to the max, but at the same time keeps culling happening.
- Instead of just merging all the surrounding houses (say 80 houses) into one big mesh, reducing Draw Calls sharply but ditching all culling

Any input or advise is very much appreciated.

Marco