I work in PAL, too. Doesn't change anything, though. Same principles for NTSC, but different numbers.
The whole point about using integer divisors for speed is that Premiere can then just duplicate frames rather than interpolate and this gives much better quality.
Unless you start with high-frame-rate originals (ie not standard DV at 25fps), you'll always see some jerkiness with slowmo, especially during fast movement and with slower replay.
Lower field first is the standard for DV, so that shouldn't be the problem. 'No fields' is unlikely to help very much for video replay - it's relevant mostly to computer replay where the display is non-interlaced.
Is your source material from video or somewhere else?