Even if you could still get PI IPv4 addresses in Asia: if your ISPs don't want to route your IP addresses then there is nothing you can do. Tunnels and LISP could solve some of your problems (I use LISP here), but you already stated that this is not available in your region.

BGP is the protocol that is used to route your IP addresses from an AS. You need both to run BGP. Blocks of 16 addresses are too small to be routed with BGP anyway. Technically you could, but nobody will accept your routes.

If you want to have your own IP addresses and route them etc. you'll have to make some investments. Because APNIC ran out of IPv4 addresses for normal distribution you'll have to comply with some very strict rules. If I recall correctly the current rules are that you have to be multihomed already, must be able to justify 25% of the addresses (which would be 25% of 256 = 64) immediately and 50% (=128) within a year. Based on your current numbers that seems unlikely. If you could then you'd need to get an AS number from APNIC and you'll have to find ISPs that want to set up BGP sessions with you. This will probably be more expensive than your current contracts. And on top of that you'd have to study a lot to learn how internet routing and BGP works or you'll have to hire someone else to manage it for you. In addition to buying the equipment needed to do all of this.

In short: it's probably not worth it for your case.

1. How should i perform failover link using BGP with same ISP?

Form the BGP neighborship loopback interface. As per this thread:

The use of a loopback interface ensures that the neighbor stays up and is not affected by malfunctioning hardware, the main benefit from using loopbacks is that it will not bring down the BGP session when there are multiple paths between the BGP peers, which would otherwise result in tearing down the BGP session if the physical interface used for establishing the session goes down. In addition to that, it also allows the routers running BGP with multiple links between them to load balance over the available paths.

2. From Router to L3 switch should i create VLAN trunk (L2) and create VLANs on Router instead of L3 switch.

No. This is called router on a stick and was popular before L3 switches were widely available. However, now that they are widely available, you should use the router to connect to the WAN and use the L3 switch to handle inter-vlan traffic on the LAN.

Doing this means that if the router fails your inter-vlan traffic will still work. Also, if you add additional routers to the topology at a later date, the switch will be able to use both of them for outbound traffic as opposed to only using your current one.

3. Or Should i do HSRP between Router to L3 switch and create VLANs on L3 switch instead of Router.

No, do not configure HSRP between the router and switch. You should instead configure HSRP between the two L3 switches so that if one fails, the other can take over.

EDIT: In response to your comment:

i heard from many source it used for iBGP not for eBGP

Here is another quote from the thread I linked to above:

iBGP generally peers using the loopback address for the reasons mentioned by Mohamed (i.e. loopback interface always stays up therefore the iBGP session stays up as long as the IGP has a path to get to the loopback interface of the peer router). eBGP commonly peers using the physical interface as there is generally only one path between the two eBGP peers. Although the loopback interface is sometimes used between eBGP peers to achieved load-balancing when more than one circuit link the two eBGP peers.

In other words, loopback interfaces can be used for both iBGP and eBGP. As you have two connections to the one ISP, you should use a loopback interface.

In regards to your other comment:

what should i use to provide redundancy/failover between Router and L3 switch?

As you've only got one router you simply can't have redundancy at the router level. If you want redundancy at the router level you'll need to purchase another router. In regards to switch redundancy, as I mentioned above you can attain this by implementing HSRP between the switches.