Saboteurs? Women and children? No, this is a good way to get free hostages. The best leverage against Ukrainian men fighting is having their families in custody.
I suspect Russia won't respect Ukraine's restriction on men leaving the country. And I suspect Ukrainian borderguards won't be anywhere close to the Russian-controlled border.
Well they'll probably all be locked up immediately.
If they talk about the war, the same as Russian citizens
Russia has given out nearly 1,000,000 passports and citizenship to Ukrainians in the eastern breakaway regions over the last two years