Actually the Yamaha can be made to do 7.1 by default regardless of the DSP program mode. Even in Straight mode all 7 speakers can be used without any need to use the Dolby/Dts up mixers. This is done with the Virtual setting. It is only in Direct mode where the Yamaha will only use the speakers present in the codec, ie mono, stereo, etc..
Ensure the speakers are connected to the correct speaker terminals. Do this with the Receiver turned off. Turn the AVR on and then you need to set up the speakers correctly. This done through the Setup menu, Setup, Manual Setup and then Configuration. Ensure the FL, C, FR, SL, SR, BSL, BSR are all set to preferably to small along with a crossover, the Subwoofer 1/2 are set and that the distances, levels are set for all speakers. Ensure the Presence, front and rear are set to disabled, if you do hot have them wired up, otherwise same as for the normal speakers. If you wish you can run the YPAO automatic setup after this, although this will likely change the speaker sizes, distance and levels. There is also a Layout section which can adjust the Surround and presence speaker types. Use the Test Tone to make sure all the speakers are playing correctly. The Volume control still works here so make sure to adjust this if required.
It is room dependent upon how accurate the Distances and level are guesstimated by the YPAO. Once the Automatic setup has been run you can go back into the menus and manually re-adjust the values using a tape measure and a SPL meter as needed. If YPAO is enabled this should not affect the Parametric EQ settings. It is best to avoid this section for manual configurations unless you know what you are adjusting.
The Yamaha RX 2050 is a 9.2 amp in that it can drive, without additional amplification, upto 7.2.2/5.2.4. For 7.2.4 you would need an additional stereo amp if this is possible. It is hard to tell without reading the manual as there are no pre-outs for the presence speakers, just zone 2 and 3.