No, as far as I could tell from its manual, the PSR-740 doesn't save those AEG and LPF settings to its Registrations, nor does it let you save and load User Voice settings-- so you could make use of those functions via MIDI while using a keyboard controller to play the PSR-740 as a sound module, or you could program the MIDI messages within a Song or Style, but I guess that's all.
Of course, if you were to run a MIDI cable from the PSR-740's MIDI Out to its MIDI In, so it can send MIDI messages to itself, then you could turn off the PSR-740's Local Control and use it as a keyboard controller to play itself as a sound module, in which case you could create MIDI song files containing "User Voice" settings that make use of those functions.
As for the "PortaTone" voice on the PSR-E models, I don't know whether it can play portamento sounds, but the name refers to Yamaha's PortaTone series of keyboard. I haven't checked to see whether any current models are still marketed using that name, but I think some of the earlier PSR-E models were. "YPT" stands for "Yamaha PortaTone," and most of the PSR-E models are also sold as YPT models that have identical features and parts except for their outer casings. And if I remember correctly, some PSR-E manuals include the name "PortaTone" within their text as well as on their covers. The term "PortaSound" is also used, which is what the "PS" in the PS, PSS, and PSR models stands for. The "Porta" is for "portable," not "portamento."
However, presumably at least some of the voices in the PSR-E models can play portamento, since the MIDI Implementation Charts for these models say they respond to the "Portamento Control" message. The only problem with that message is that it ignores the "Portamento Time" setting (and the PSR-E models don't respond to that message, anyway), which means that if you play portamento notes using the "Portamento Control" message then it uses whatever portamento time is preprogrammed into the voice itself. Aside from the synthesizer voices, the voices which might be promising to check for portamento include the trombone and possibly the guitars.