I would like to know lf it comes unlocked and I can put a foreign sim card and use it immediately.Thanks

I edited the title. Welcome. Yes, it does come fully unlocked.

By law is is factory unlocked and will work with AT&T, TMO and all international carriers. The Vz 5s is probably the most versatile smartphone in that it will work on both the CDMA and GSM networks.

But will it only work on Verizon's MEID (for CDMA)?

In the US, Verizon will only activate phones on its network that it originally sold. I think they have some other program where they will activate other phones of certain models, but I'm not aware of anyone successfully getting them to do so.

Sprint may have similar policies. I don't know.

Nonetheless, the Verizon iPhone 5s will do CDMA roaming on CDMA networks in the US and overseas per Verizon's roaming agreements.

It's too bad you can't buy a Verizon 5s for full price from Apple. But for those shopping on Craigslist or eBay and can find a clean ESN unit, it's worth considering.

Here's the bandwidth/spectrum summary on both the Model A1533 [both CDMA and GSM versions] sold stateside:

http://www.apple.com/iphone/LTE/

iPhone - locked to a particular carrier (like Verizon) - is just a record on APPLE server. So if you put in your SIM card and iPhone does not complain (need WiFi connection to APPLE server) - it is unlocked and good to go.
Regarding LTE-4G - Verizon IPhone 5s - support a lot of bands (LTE frequencies) - but not all of them. People complain that 2600 frequency - used in Europe is not supported by any of USA models.

iPhone 5S A1533 LTE 700/800/850/900/1800/1900/2100 USA AT&T, T-Mobile, Verizon
iPhone 5S A1453 LTE 700/800/850/900/1800/1900/2100 USA Sprint, United Wireless
iPhone 5S A1457 LTE 850/900/1800/1900/2100 Europe/Middle East
iPhone 5S A1530 LTE 800/850/900/1800/1900/2100/2600 Asia Pacific
iPhone 5S A1518 LTE 800/850/900/1800/1900/2100/2300/2600 China

It's pretty much been that way with CDMA providers from the outset. I did think though that there was a federal mandate that it's possible that you could bring your (compatible) phone with you that if the phone was unlocked it could be used on any compatible service. With GSM you've always been able to use any unlocked device anywhere (provided it was frequency compatible.)

Just wanted to say you actually can do so. Just walk into an Apple store and tell them you want to purchase a Verizon iPhone device only. That's what I did, and it worked just fine.