- physically soldering a headphone input jack thru the speaker terminals (might include drilling the side chrome panel to fit the jack)
Look at that topic. You might consider just using the microUSB connector :
[Only registered and activated users can see links. ]

- on my old 855, there were games included like Solitaire, Sudoku, Space Thrower, Temo, Rock Slide, Interceptor, Boxing. etc..
can these games also be flashed to the 34xx?
No, not possible. 800 series are linux based that is why they had games.