fdonat wrote

A cluster should solve my needs.

Why a cluster? A cluster only lets you address the EAPs as one device for administration, which makes sense if you have a dozen of them to administrate.

To have wireless roaming, just set the same ESSID on both APs and connect them to the same subnet. The wireless adapters of your devices will seamlessly change the BSSID of the APs as needed.

Which APs should I use? EAP115 or EAP220?

Depends on your needs. The EAP110 may also be a choice, it uses so-called passive PoE and comes with a PoE injector. The EAP115 needs an 802.3af-PoE-capable switch such as the TL-SG105/108PE if you want to provide power over the data cable (else you would need to use the included power supply and a mains plug). The EAP220 gives you dual-band WiFi, but it needs an 802.3at-capable switch, which are more expensive than 802.3af, or the included power supply. My favorite EAP for home installation is the EAP120 powered through a TL-SG108PE. See the comparison table on the product site (scroll to the end): http://www.tp-link.com/us/products/details/cat-5692_EAP115.html

Do I need a PC to run the EAP configuration-program or can I do this on one AP and it broadcasts the config to the other?

No, the EAPs have a built-in web UI. But you could use the EAP controller to manage the EAPs (again makes not much sense for two EAPs unless you need user management, guest networks, statistics, etc.). The models supporting cluster and config broadcasts are nice, but since you should use different WiFi channels on the EAPs, it's not of a big advantage to have config settings being broadcast to the two devices. Usually, you need to configure the devices only once, but not every other day, do you?

Would a VOIP-call be supported to "roam" as well?

Sure, if you use the same ESSID, every IP-based application will continue to work while switching an AP in the same subnet if you are leaving the WiFi cell of the other one even if you use different WiFi channels (what you should). But depending on handshake of your phone's WiFi adapter, there could be a short delay or a short break, which even happens with VoIP on wired lines occasionally.

DocJones wrote

Contrary to R1D2's claim, the EAP220 is 802.3af-compatible as well (does not require 802.3at -- see second bullet point at top of page), and can be used with any 802.3af power injector; from what I can see only the EAP3xx series (such as the EAP320, see last bullet point at top of page) needs 802.3at.

You're right. TP-Link got it wrong in their comparison table on the linked EAP115 page which claims the EAP220 would need 802.3at - it does not. It consumes max. 9.6 watts, which can be supplied by a 802.3af switch easily. Thank you for the clarification!

DocJones wrote

Oddly, I just looked at the box for my EAP245 and that claims "802.3at" right on the front. I'm now more confused than ever... but my 802.3af injector seems to be running it just fine on a ~50ft length of Cat 5.

Depends on cable length, type of power supply and actual power consumption if fully loaded (e.g. 2.4 GHz and 5 GHz clients simultaneously connected). Maximum guaranteed power for 802.3af is 12.95 W due to possible power loss on long cables and use of a switching power supply. According to the specs the EAP245 consumes 12.7 W so it operates on the possible limit of 802.3af. Depending on the cable the limit could be slightly exceeded by the EAP245 under full load under certain environmental conditions (it's usually recommended to have a 20% to 30% reserve for any power supply, therefore the specification of 802.3at for the EAP245). But with ~50ft cable length you should be on the safe side with 802.3af.

What's funny: on the German TP-Link website they specify 802.3af under "Functions", but 802.3at under "Specifications" for the EAP245. So one can probably choose either one. :D