A few general notes; my experience is more in scientific computing than game dev, but the needs of DF seem to be closer to the first than the second most days.
* If you are using Ubuntu, I strongly recommend a LTS (Long Term Support) version, usually either the current or previous version. These are supported for five years. Non-LTS releases are only supported for 9 months, and are not generally suitable for production use. 14.04 LTS (Trusty Tahr) is supported through April 2019, and 16.04 LTS (Xenial Xerus) is supported through April 2021. 16.04 has only been out a few months, though, and there may not be as much useful info out there for it; 14.04 is probably the safest choice.
* Linux packages come in three, not two, general levels of relevant processor support: i386, i686, and amd64 (aka x86_64). For some packages & libraries, it is possible to have two or even all three loaded; for others it's a mess. My general suggestion, and the general trend elsewhere, is to have the base system on pure 64; and some sort of sub-system (Virtual Machine, chroot setup, docker container, etc.) to handle 32 bit compilation; although some still prefer to just have a completely separate entirely-32-bit system (virtual or physical) for that. If your needs are simple you may be able to get away with a multi-library single system and compiler flags, though.
* Try really hard to avoid building packages yourself these days. yum or apt-get are really your friend; and if you stick to a standard set of repositories the odds that things will "just work" go up.
* Darwin, the Mac underlying environment and particularly compiler, is careening further away from BSD, Linux, gcc and the rest of the world with each release. Where I work, we've had to largely give up on it for compiling; we use
HomeBrew to set up a full gcc chain and work with that. (Admittedly, however, the software we're using doesn't need to do much if any Mac-specific stuff.) Anecdotally, for instance, gfortran doesn't even remotely work on a modern stock (Darwin) Mac, is a hassle to get set up under fink, and "just works" under Brew once you install the gcc chain and tools.
* XCode has gotten very picky about only installing more recent versions on more recent OS X versions. Generally, you're OK for about one to two versions back, but rarely more these days. This may not be an issue for DF currently.
* More of my experience is on RHEL-based Linux than Debian-based Linux; if you end up dabbling on that side, a current version of RHEL / CentOS / Scientific Linux 6.x is probably easier to get running on older hardware than the newer 7.x. Conversely, if you end up with a shiny new machine, supporting all the modern boot stuff may require 7.x.
I've unfortunately got some deadlines for the end of the month, but if things still need testing in July I'll try and find the time to spin up some VMs and compare things.