For Vietnam:

1. The armor style was generally identical to China's. This blog (https://nghiencuulichsu.com/2013/03/06/ao-giap-dai-viet/) has pictures of some artifacts, the flavour text I cant vouch for because the blog does not cite their sources. The official Vietnam Veteran organization at HCMC (http://www.cuuchienbinhtphcm.vn/index.php?option=com_content&view=article&id=5269:giap-tr-thi-xa-nc-vit&catid=86:theo-dong-lich-su&Itemid=196) also has an article about historical Vietnamese armors, but again, no source, though they are more official than the private blog with pictures above. Aside from the 2 websites above, I cant find any resource that actually cites their sources nor any professional academic source in both English and Vietnamese.

2. The northern Vietnam region used to be colder than it is now during the Little Ice Age period. Even in the modern day, it's still sub-tropical instead of tropical. So it wasnt that hot.

3. Logistics: Horses, elephants, and ships were the favourite. Elephants served as both tactical tanks and trucks. Human messengers with horses were also used. For long-term campaigns, the army has a policy to set up a hamlet where they are stationed at and grow their own food to feed themselves in addition to the dried food they carry. This policy is called "ngụ binh ư nông" (寓兵於農), dating back to the 10th century Đinh dynasty. It was used to great effects during the 3 Mongol invasions, the Southward Expansion, and the wars with France and the US, and is still an official doctrine of the PAVN today. For more details about the ngụ binh ư nông policy, you can look up information about any of the war above. The Củ Chi tunnel from the war with the US was one such example of a ngụ binh ư nông hamlet.

4. Jungles are only something to penetrate for the invading armies. Historically, from the Trưng sisters era till now, the jungles and the rural areas have been considered the backup capital for the Vietnamese armies. During the Mongol invasions, whenever it looked like the Mongols would arrive at the capital, the Trần dynasty would pack up the capital there to move to the rural areas and the surrounding mountainous jungles, leaving only a token group of soldiers left to buy time. This same strategic retreat was used again in 1945: when the French returned, the Viet Minh in Hanoi packed their HQ base and moved to the surrounding mountainous jungles in the Việt Bắc area, while the Viet Minh in the south moved their HQ to the rural areas surrounding Saigon (such as Củ Chi) and the nearby cities.

5. Tactics: Ambushes, suprise attacks, traps, waiting out the enemies, cutting off enemy supplies, strategic retreat. This is best described by the tactics during the second and third Mongol invasions. During the second Mongol invasion, after packing up the capital, the Trần set up a temporary capital in their hometown and a second backup capital in the Việt Bắc area. The force in Việt Bắc's mission was backup when needed and rob the Mongol's supply ships and cargos. The force in the Trần hometown, with the 2 emperors with them, both acted as bait to wear the Mongols out, to bait them into leaving their supply force behind in their haste to give chase, and to be the surprise attack harrassment force when the opportunity arrived. Before they left Hanoi, the Trần had ordered that all food be carried with them, all things that could not be carried was torched down. As a result, when the Mongol arrived at Hanoi, the fields were salted and not a grain of rice was left for them. Since the Mongol was infamous for not carrying a lot of food with them (and the Vietnamese knew this), all the Vietnamese needed to do was wait for the Mongol to starve and fall sick to launch the final ambush at Hanoi for slaughter. In the third Mongol invasion, the Mongols in the central government smarted up and order the main force to carry with them huge supply ships, but their generals were still hasty and easily baited into leaving their slow supply ships behind. Both the supply ships and the main force ships were routed, trapped by river pikes, and torched down by ambush archers from the river banks during the second Bạch Đằng battle. The Điện Biên Phủ battle was largely identical to the ambush setup against the Mongols in Hanoi back in the second Mongol invasion, just with modern weapons and tanks. In the same vein, the entire campaign against the French took more than a page from the campaigns against the second and third Mongol invasions, just longer in time frame because modern supply line helped the French extended their hold of Hanoi compared to the Mongols.

It all rather depends on the period your looking at. The military of, say, Thailand in 1500 was wildly different to that of India in 300.

One word of caution- the great majority of India is not tropical in nature, but arid, punctuated by large mountainous outcrops which were easily fortified. That's also true of parts of Thailand and to a lesser extent Burma. There you wouldn't encounter rainforests at all, really.

In regions such as this, cavalry was king. There were two basic models- very heavily armoured cavalry, backed up by elephants- themselves heavily armoured- and later, artillery. Slow paced, but hit hard; or light cavalry and light infantry, using raiding, guerilla tactics, commandos, and sniping (even in a very early period).

In more humid areas, I'm aware that logistic was largely done by riverboat- both Ayutthaya and Taungoo, for example, operated large riverine navies.

But it's hard to make any recommendations without specifics. What exactly were you looking for?