can i update my ultra to 4.4 ? topic

hi all

i bught droid ultra limited unlock gsm from ebay / and now it work perfect in my carrier in my country . in asia

i have quastiones :

phone is for ever gsm unlock ?
can i update to android 4.4 ?
is this possible to phone be locked again after update new rom ?

please help me . i affried to update or change my rom ::(