Wow you guys seem to really know your stuff. *thumbs up*
Nonetheless, I feel like answering based on my own simple definitions/answers.
*country with overvalued?? exchange rates tend to experience a decline in exports
When one country's currency is overvalued, then it means it costs more for other countries to buy their exports- and as a result, the exports will decline.
*the value of currency can influence inflation & intereset rates
There are wayyy too many possible connections to talk about here in a simple post.
For example;
Strong currency -> More imports -> Imported inflation -> Interest rates rise to fight inflation -> More foreigners/speculators buy local currency to invest -> Currency strengthens
But then businesses will have less exports, possibly leading to interest rates falling to stimulate them and weaken the currency, etc..
People USUALLY speak of interest rates affecting value of currency where higher interest rates will attract foreigners to invest in domestic banks, and vice versa when interest rates are low- this is a much more direct relationship.
When a large number of investors sell holdings of FOREX it can destabalise an entire country--> does this have any relation to portfolio investment?? i.e Asian Crisis
For a currency which is largely traded by speculators such as the Australian dollar, it can push the currency around significantly. Other countries such as Brazil have had much more unstable currencies which if someone sold a considerable amount, the value of the currency will fall substantially, worsening the terms of trade/purchasing power of the country's people.
Portfolio investment could be affected by the sale of holdings of FOREX in the sense that there are people who are purely speculative and are hoping to make profits from movements in the currency (rather than actually using the money for a productive purpose), and as a result, if someone sold a lot of a currency, and everyone else followed suit, the people who are left still holding the currency are worse off.