Your rig will always start from 7.000 MHz and will not remember the last used frequency unless you install the AA batteries... which last not that long.? F5RCT mod extends the battery life significantly.? But if you do not mind the fresh start every time - it is OK.
If you are a CW guy, you will be disappointed with the FT-980 original keyer.? It employed the Curtis IC that was not very user friendly.? I personally could not use it and built my own keyer.? I assembled it on a Vector board so it does not look too pretty, but uses the P98 and works very well.? I had plans to lay out a board for it and have some made but... it became a back burner project.
At some point I did a research on Yaesu optional keyers and noted that a similar design was used in other models i.e. FT-ONE.? It may be worth looking at.? Or, maybe someone on this list has better insights on the keyer compatibility with other models.? BTW, at some point Yaesu quit on the Curtis design and used another IC.? Hopefully that fixed the problem...
With no CW filter installed you will have the same BW as in SSB mode.? Width/shift may help a bit but not much.? The CW filters are rare but show up on eBay once in a while.? swap.qth.com or qrz.com are also good places to look at.? You may post a WTB messages there.
One thing you may want to take care of is to set the LIN AMP in OFF position.? I had issues with slow leading character ramp-up when this switch was ON (and no PA).? The first CW character was severely truncated and stations replied to me as II4PL? HI.