Visa questions

Apply online. It is fairly cheap and quick. They offer online chat to guide you through your options. My experience with them is much better than travel agencies in the States.

I am very happy with my experience with them last Jan and will use them next Dec. They are much better than my six previous visa experiences.

It will cost you about 20 minutes to get out of the airport.

You say you want to stay in Vietnam between 3 and 9 months.
There are discussions here about whether you can currently get a 1 year multi-entry business visa. Some online agencies offer it, some don't. And some differentiate between US and non-US 1 year multi-entry business visa.
You have to ask the online agencies or try.

You have 3 options.

As a Spaniard you can enter Vietnam 15 days without a visa.
a) Then you can apply for a visa in Vietnam through an agent, or
b) you can apply for a visa in Vietnam through an online agency.

2)
You apply for a 3 month tourist visa at the Vietnamese Embassy in Spain.
After 3 months, see 1a) and 1b)

3) You apply for a visa-on-arrival (tourist or business) through an online agency.

https://getvisatovietnam.com/apply-visa-online/
http://www.e-vietnamvisa.com/apply.html
https://www.vietnamvisacorp.com/apply-visa?action=step1
https://vietnamvisachoice.com/application/
https://visaonlinevietnam.com/apply-vietnam-visa-form
http://www.vietnamvisapro.com/en/embassy/175-spain.html


In the other thread I saw that you want a driver's license.
I think with a 3 month visa you can't have your driver's license converted into a Vietnamese driver's license.
That's why I think a 1 year multi-entry business visa would be the best for you (if you get one) though it's probably the most expensive.

Regarding driving license, you can ask https://dichthuat.org/en/  (translate996[at]gmail.com / phungocviet[at]gmail.com).
I uesed this translation office for the conversion of the driving license (500k Dong) and for applying the TRC.

Thanks You for your Answer.
It's, a clear  explanation  of the issue.
I will have it in my mind.