hello, I have a need to change different strings in the engliah language of limesurvey

using version 2 latest release

i downloaded and installed poEdit and it is working weired

please correct me if i am wrong:
1- i opened the po file from the site here
2- all translation box is not filled (English) is that mean i have to go through them all and copy paste one by one from original string to make my own!? i want only to change like 100 string inside using find/replace...

what happens if i keep some phrases not translated!? will it just work as the string which is not translated or i have for sure to copy paste everything in order to work!?

3- after this is done, is it enough to replace the .mo file inside the languge LS_messages or i have to do something more in order to sychnorize the new language in limesurvey internal files?

can anyone give us more hints about this poEdit thing with limesurvey, i couldn't find replace button and also can't select all phrases and copy/paste them into the translation box in order to adjust the langugage according to the need

please advise