i never heard different breakers being or not being compatible with a Murray box. Can you help me by explaining a little on that?
CH, QO, Pushmatic, Zinsco and FPE breakers all have very unique shape and it's not possible for brand X to anywhere near fit Brand Y.
However, BR, HOM, GE and Siemens/Murray and Siemens/ITE all are 1" wide breakers with coarsely similar form-factors. They're similar *enough* that a competitor breaker will usually seem to "snap in" to the bus stabs. However, the bus stabs are actually different in shape (not least, due to patent protection each obtained on their stab) - and the clip on the breaker will not mate *properly* with the competitor stab. It will have corner contact in a tiny area instead of the broad surface contact it's supposed to. This will seem to work under low load, but will stress out quickly under heavier load, and eventually cause heating, arcing and pitting which will permanently ruin the bus stab, making that breaker space a "dead zone". Not what you want!
The risk of fire makes it a Code violation, specifically 110.2 which requires approved components and 110.3(B) which requires you follow the instructions i.e. use the device as tested and approved.
UL does approve *certain* competitor breakers on a case by case basis; these are called UL-Classified.: Eaton CL (CLassified, get it?) are approved for HOMeline, Siemens, and GE Q panels. Eaton CHQ and Siemens QD are approved for QO panels. This is nice because it gives you access to some of Eaton's exotica e.g. remote-control breakers that nobody else makes.
regarding breakers 13 and 15 - i can see why you would think it is a 220. it actually is two different 110 circuits. the one with the red wire - the prior owner and 12/3 wire and used the red instead of the black.
I bet if you look other places in the circuit, you will see the black used instead of the red. Learn more about a Multi-Wire Branch Circuit
-- that's what this is. It's a very slick way
to get 2 circuits' worth out of a single /3 cable - however, it is one circuit, a "multi-wire branch" circuit.
While you may be grandfathered, the reason to fit handle-ties is to keep you from getting nailed when you are trying to maintain it. For instance if you turn off the red-wire breaker and then take the circuit apart, the moment you separate neutral, you will discover the black is in use after all, when you get nailed by current moving on the neutral from the black wire!
MWBCs must be phased correctly. The two wires must be on opposite poles/phases to avoid overloading neutral.