I think you make a lot of valid points, Meadow. The montage and song come out of nowhere, and includes scenes from episodes that haven't aired yet, including the Christmas special. The episode introduces Redstone warren, which will be important later on in the series, but the trip in this episode feels rather pointless and annoying.
I wasn't much of a fan of the subplot about Fiver either. In an earlier episode, Hawkbit made similar accusations and Fiver handled them well, and now he is left completely depressed. Also it isn't pleasant seeing my favourite character suffer like this

As for Broom's name, it appears to be a
type of shrub or something. Although the odds are that most viewers will probably end up thinking of that thing we use to sweep the floor instead

Please tell me the next one is better. XD
More or less...it's a filler episode about a farm raid. It's not as bad as the season 2 fillers, but it's still a filler, and somewhat breaks the continuity with the sudden introduction of Primrose's kittens...The series has some great episodes, but also some really bad ones.