So first off I should mention that I'm not a part of the PAL / Minnow Support team, but nevertheless I should be able to answer your questions:

Does PAL have a different curation algorithm?

Yes, I believe PAL is set up with a 50/50 author/curator split and a slightly higher than linear reward curve. You can see the exact settings in their whitepaper post

Does it have a team to improve the front end?

@eonwarped is the developer working on the Nitrous codebase (fork of condenser) and the Steem Engine team is also working with other front ends like SteemPeak to provide custom, whitelabel front-ends that support SCOT tokens as well.

How is the team going to control the infrastructure cost?

The infrastructure costs are extremely small, around maybe $100 / month, so that shouldn't be an issue. Steemit, Inc's costs are primarily from running their api.steemit.com full node, and even then they were astronomically high. PALnet does not run their own full node currently (at least not a usable one), however hopefully with the release of MIRA they should be far more cost efficient to run if needed.

Why should I post here rather than Steemit.com?

It doesn't really matter where you post from as long as it goes to the Steem blockchain. As long as you use the "palnet" tag on your post you will be able to earn PAL tokens from anyone with staked PAL tokens who upvotes your post. The upvotes can also be done from any front-end as well.

The reason you might want to use the palnet.io website instead of steemit.com is because it only shows posts with the palnet tag, so if you're only interested in that specific type of content you can go there.

Perhaps a better example of this is the splintertalk.io site for posts about the Steem Monsters / Splinterlands game. Many people just want to post and read posts about the game, so they can go to splintertalk.io and not have to filter through all of the unrelated content on steemit.com.

Also the new sites have a few features that are different than steemit.com, and will likely be getting more over time as development continues which will help to further differentiate them.