When the score is like this, should the viola be divided into 1 and 2 like the violin?
Or is it better to input the chords on a single line, then use the condensing feature before entering the text?
After using condensing, when it shows Viola 1, Viola 2 like this, is there a way to hide the condese number for a specific instrument?
You can use the divisi feature, and condense the divisi.
It will allow you e.g. to show this section condensed in the score and uncondensed in the part.
I do prefer to use the divisi as much as I can for the strings (even if for very short occurrences I sometimes just enter the notes as double stops). I think some other users don’t seem to use it very much. It also depends on the style of music (are the divisi very simple, as in your screenshot, or are they more complex…)
Yes, with divisi you’ll have control over the 1. 2. in the staff labels, either as a Layout Option (Staves & Systems > Divisi labels > Untick Show section names…), or one by one: open the Divisi dialog and set Show section numbers to hide.
For me, the divisi feature is best suited for when the music absolutely needs to be put on multiple staves. In a situation like this, where the performance direction is essentially “play these chords divided” in the first bar and then “play these as chords” in the following bar, I probably wouldn’t bother using a divisi change and would just use staff text to input the “div.” and “unis.” manually.
If this is the only divisi in the violas, or the others are similar, I also wouldn’t bother with formal divisi but put the music on a single staff in the part.
Exactly - don’t divide the violas into two separate parts! Unless there are exceptional circumstances that make that the best way to do things - but that would be rare. Don’t do it routinely, anyway.
As others mentioned already, this on it’s own isn’t a big deal. But the potential issues will come if you have multiple instances of divisi or solo/gli altri, depending on where they fall in relation to each other and in your score/part layouts. You could end up with a condensed divisi passage printed twice on two divided staves. For me, the most foolproof method is to use the divisi feature for pretty much everything, even if it’s super simple, and then use condensing changes in the parts to control what stays on one staff and what splits into multiple staves.
According to my son, who is violist at the Opera of Paris, no.
Ravel and Debussy use frequently this kind of indication ; the parts will reflect this divisi, and the instrumentalists know perfectly well how to manage this within their section of the orchestra. No need to rack your brains. 
Thanks.
After entering each text, how should I separate the files into Viola1 and Viola2 when working on parts? Is it better to duplicate Viola and delete the unnecessary parts?
you do not make separate viola 1 and viola 2 parts. you make a singular viola part that contains both.
No need, just give all the players the same part. Orchestral pieces (even ones with more extremely divided sections) very rarely use different physical parts for individual members of one of the 5 string sections. The string players will all know how to divide the section: since string players all share stands, the person in the outside chair (the seat that’s closest to the audience) plays the top part and the person in the inside chair plays the bottom part.
