The answer depends on a LOT of things. Most importantly country of origin.
If you’re from Latin America, most people won’t even notice. Since we already have huge amount of Latin American immigrants, so we are used to it.
If you’re from a “white” country, it’s very important that you are respectful to the local culture and try to genuinely learn Spanish. This is mostly a problem with tourists instead of immigrants, but most Spaniards hate with passion when foreigners complain about things not being in English/German/french/whatever.
If you’re from a “black” country, it depends on where you move to. In some parts of Spain you’ll inevitably face a lot of racism. In others, you’ll find groups of people that will try to protect you. But as always, there’s always at least some racists.
And of course, don’t do crime. But that goes for locals too.
And I think this is a global advice. But people will instantly judge if you are lazy or hard-working. If you help your local community without asking much in return, people will probably talk about how hard working you are, and even racists will probably say “for being for country X, he’s a nice guy”.
Having more people always adds overhead. It’s not only software developers.
You don’t need to have two developers working on the same piece of code, you can have each one working on a feature. And different teams can develop different projects/products. If a project takes 1 year to complete but you want an output of 2 projects per year, you don’t need to overwork your current employees. You can hire a new team so there are 2 simultaneous projects being worked on at the same time.