First, thanks for this great forum, a real life-saver

I am trying to obtain ab-initio models of my protein, of unknown structure. I know it is tetramer (made up of 4 heterodimers), so I used P4 as symmetry set, all other values as default.
1. I have collected data using to line configurations, 1.5 m and 1.0 m sample/detector distance, to have better q range. When modelling with DAMMIF, these give quite different models. Is this congruent? (I am struggling to merge them, but there is a binning error; same number of data points in both but wither q-range in one of them)
2. When refining with DAMMIN (ATSAS 2.7.1), using DAMSTART.pdb, I cannot set a symmetry: is this correct?
3. The DAMMIN refined model is expected to be better than the most typical model retrieved by DAMCLUST? To choose between the two, should which one fits better (using DataComparison on ATSAS)?
4. Is there a way to obtain dimension of the ab-initio model? I have homology models of the protein which I attempt to try to superimpose.
Thanks!