My experiences with hiring and paying overseas devs have been pretty easy (I'm in the US).
We have paid using SWIFT transfers, which sometimes require a bit of work to set up, but nothing too onerous - it's like doing any complicated transaction at a bank. Once set up, the recurring payments are generally trivial - as you said, we get an invoice, send payment, and things are merry.
Tax-wise this is an expense like any other to our US-based company. Note that in this case the developers actually LIVE overseas. If somebody is in the US but is not a resident / authorized to work, then it's a whole different story.
We have paid using SWIFT transfers, which sometimes require a bit of work to set up, but nothing too onerous - it's like doing any complicated transaction at a bank. Once set up, the recurring payments are generally trivial - as you said, we get an invoice, send payment, and things are merry.
Tax-wise this is an expense like any other to our US-based company. Note that in this case the developers actually LIVE overseas. If somebody is in the US but is not a resident / authorized to work, then it's a whole different story.