Vietnam's defense budget is covered by the government.Is Vietnam's defense budget today fully covered by the government? Or it is partially paid by the government, partially paid by the military enterprises?
Can the government appoint any non-military persons to the management positions of Viettel and other military enterprise, or it is the self-appointment made by the military itself?
Can the normal legislation/discipline system work for the military enterprises? Or it is self-disciplined by the military itself?
Regarding Viettel's management positions, I'm not sure, currently the chairman is still military man and it seems the top positions are still occupied by the military:

TGĐ Viettel Construction được thăng quân hàm thượng tá trước thời hạn - Viettel Construction
Ghi nhận những thành tích xuất sắc, góp phần dẫn dắt Viettel Construction phát triển vượt bậc trong những năm qua, Bộ Quốc phòng quyết định thăng quân hàm Thượng tá trước niên hạn cho ông Phạm Đình Trường - Tổng Giám đốc Viettel Construction.

But the position is appointed by the government, not the army.
A chairman cum general director will be the State representative to Viettel to implement all rights and duties. The chairman will be nominated by Prime Minister Nguyễn Xuân Phúc upon the National Defence Ministry’s proposal and agreement of the Central Party Committee.
According to the new organisational and operational charter, Viettel will have no more than five deputy general director.

Viettel renamed Military Industry and Telecoms Group
Military-run telecommunications company Viettel Group was officially renamed Viettel Military Industry and Telecoms Group and recognised as the national defence and security enterprise with 100 per cent State-owned capital.
vietnamnews.vn