Disclaimer: Character build advice does not have one objective solution.
How will my game play change depending on what feat selections I take? Are any of these underpowered?
Feats are limited choices, and each weak choice means an opportunity cost of something potentially better. Your "Second Option" list contains some weak options.
Cosmopolitan is not useful for a Bard. As a bard, you gain access to spells like Comprehend Languages and Tongues, which let you pick any language you want for a period of time. If you really want permanent knowledge of a specific language, then spend a skill rank in Linguistics to become fluent.
Gaining two more class skills is nice, but bards already get most Charisma, Intelligence, and Wisdom based skills as class skills. Plus, you already get plenty of skill points per level, and can take advantage of the Versatile Performance class feature to use a single perform skill in place of multiple other skills.
Also, Eschew Materials is very circumstantial, and is often considered too circumstantial to be worth a feat. Just buy a spell component pouch, and you will have the same benefit most of the time. In case you lose your physical spell components, a bard still knows some spells that don't require material components.
Is Expanded Arcana as powerful as I hope? I'll have bonus spell slots from high CHA, won't extra spells known be really awesome?
Expanded Arcana is indeed powerful, but may have diminishing returns. Bards have rather slow spellcasting progression, and so taking Expanded Arcana too many times will end up giving you a lot of low-level known spells. And that may seem like more spells known than you really need, especially when street performer bards have the "Madcap Prank" performance with a flexible selection of targeted debuffs. Expanded Arcana is a poor choice for a feat at low levels, when buying a wand of those same low-level spells is much cheaper and more efficient.
Yes, more spells per day is awesome. But perhaps you are underestimating the value of your Use Magic Device skill. As a bard with a very impressive Charisma modifier, if you invest in UMD, then your skill bonus should be high enough to reliably cast from scrolls and wands of other classes. And if you cast from scrolls or wands, then you can save your daily spell slots for when you need them.
Am I missing any others off this list? Anything else you need to know about my character?
That's hard to say, and maybe impossible to answer. You may want to Google search along the lines of "pathfinder bard guide" or "pathfinder bard feats", to see which feat choices are often recommended, such as Lingering Performance to get the most from your performances. As a caster bard, you will benefit from abilities that increase the DC of your spell's saving throws, so perhaps Spell Focus for Enchantment or Illusion will be useful. Beyond that, there is no single or best way to build a caster bard.