With visual telescopes, bigger aperture is better. Not only do they collect more light but they are able to resolve more detail. 8" or 10" Dobsonians will offer much better viewing, but at the expense of size and cost.
Also, a solid-tube 6" Dobsonian may outperform the Heritage 150p in areas with a lot of streetlights, as the collapsible design can let in a lot of stray light. I made a shroud for mine, which helps, but it isn't perfect. You can't store a 6" solid-tube Dobsonian on a shelf though.
Finally, don't underestimate a pair of 10x50 binoculars. You won't get a great view of the planets, but the skies are much more impressive through them.
Aperture rules until the work to set up means it sits unused.
The objects you mention are bright (and small) and can be seen in anything, including nothing, which fills department stores with small scopes known to amateur astronomers as "Hobby Killers".
So immerse yourself a bit, pick up some language and basics, then find a local club to try before you buy, clubs or generous members may have a loaners scopes so you can figure out where you want to be on the what you can see v.s how much effort you can put in scale.
cheers